FIS: International Ski Federation ("Fédération Internationale de Ski" in French), the governing body of all freestyle skiing events for the Olympics. 

Freeskiing: A new-school ski movement, heavily influenced by snowboarding, that became popular starting in the late 1990s. Includes the Olympic disciplines of halfpipe and slopestyle, as well as the non-Olympic discipline of big air.

Alley-oop: In halfpipe competition, when a skier rotates 180 degrees or more in the uphill direction. This increases the difficulty of a trick because the skier is spinning against their direction of travel. 

Booter: Another term for a slopestyle jump. Sometimes referred to as a "money booter." 

Box: A jib feature that has a wider surface for sliding than standard rail features. 

Cannon: In slopestyle competition, a rail or a box extending off a jump at an upward angle. Skiers can slide over the cannon rail, then when coming off of it, will have more air time than usual rail features allow. 

Cork: An off-axis rotation. If a skier inverts twice, the trick becomes a double cork. A third invert makes it a triple cork, and so on. 

Deck: The top horizontal portion of a halfpipe wall, above the lip. 

Direction: There are four different spin directions in freeskiing: rightside, leftside, switch rightside and switch leftside. They refer to: A) which direction the skier is facing when they approach the takeoff, and B) which side the skier is spinning toward when they start the trick. When evaluating a run, judges want to see skiers execute tricks in as many different directions as possible. 

Grab: The way a skier grabs and holds their skis with their hand(s) during a trick. This exhibits control over the trick, which judges want to see, and adds to a skier's personal style. There are many different types of grabs, and they are based on which part of the ski is being grabbed. Common types of grabs include mute, safety, tail and Japan. Judges may reward skiers for performing a variety of different grabs during their run. 

Flat bottom: The area in the halfpipe between the two walls. 

Gap: A part of a trick where a skier jumps over some part of the rail and either touches the rail on the end or lands on another rail. 

Halfpipe: An icy, sloped, U-shaped course. Skiers go back and forth between the walls of the pipe, performing a trick each time they go up the wall and above the pipe. The length can vary, but the standard height for a competition is 22 feet. Also called a superpipe. 

Jib: A slopestyle term for a surface other than snow, such as a rail or box. 

Jibbing: Riding on a surface other than snow. 

Jumps: In slopestyle, skiers will execute tricks off multiple jumps, which each feature a takeoff and landing. Although slopestyle courses vary from venue to venue, a typical course will have 3-4 jumps. The size of jumps also varies, with bigger jumps allowing for more difficult tricks to be done. Also called booters or kickers. 

Kicker: Another term for a slopestyle jump. 

Kinked rail: A rail feature that includes at least one spot where the angle of the rail changes as the skier slides over it. 

Knuckle: The top of the landing zone on a jump. 

Leftside: When a trick is executed by spinning to the skier's left side. 

Lip: The top edge of the halfpipe wall. 

Pretzel: A type of rail trick in slopestyle. A skier spins onto the rail in one direction, then stops their momentum and spins off the rail in the opposite direction. For example, a skier may spin a leftside 270 onto a rail, then reverse their momentum and spin a rightside 270 off the rail. This would be known as a 270 on pretzel 270 out. 

Rails: In slopestyle, these are the non-jump "terrain park" features – basically, obstacles that are meant for sliding over. Many rail sections feature multiple options for skiers to choose from. Although slopestyle courses vary from venue to venue, a typical course will have 2-4 rail sections. Also called a jib section. 

Rightside: When a trick is executed by spinning to the skier's right side. 

Spin: A half-rotation is a 180, a full rotation is a 360, and so on. All tricks in halfpipe, as well as jump tricks in slopestyle, will be measured in multiples of 180 degrees. Rail tricks in slopestyle will be measured in multiples of 90 degrees. 

Slopestyle: A downhill course consisting of both jumps and rail sections. Skiers perform tricks at each section of the course and are then evaluated on their run. 

Superpipe: A type of halfpipe with a much larger and smoother transition than a standard halfpipe, allowing riders to get higher above the lip. Superpipes are standardized at 22 feet in height and are used for all major competitions. 

Switch: Skiing backwards. The skier's back is pointed toward the bottom of the slope, while the skier's front is facing toward the top. Sometimes called "fakie." 

Switch up: While sliding on a rail, the skier jumps, spins 180 degrees (or more) in the opposite direction, and lands back on the rail. Also called a swap. 

Transition: The curved surface of the halfpipe walls between the flat section and the vertical portion of the wall. 

Twin-tip: Skis with the tips on both ends slightly bent up to allow for easier skiing both forwards and backwards. Used by all halfpipe and slopestyle skiers. 

Unnatural: When a trick is executed by spinning the opposite of a skier's preferred (or "natural") direction. For example, if a skier finds it easier to spin to their left, then a rightside spin would be their "unnatural" spin direction. 

Zero spin: The skier takes off switch, then lands switch without spinning or inverting. 

A note on trick names in freeskiing: The names of tricks will often include the spin direction, number of corks (if any), degree of rotation and type of grab. For example, a skier might land a switch leftside triple cork 1440 mute grab: In this example, the skier would be approaching the jump backwards (switch), spin to their left (leftside), then simultaneously do three inverts (triple cork) and four full rotations (1440) in the air while holding a mute grab. 

Absorption/extension: A component of a skier's "turns" score. As a skier moves through the course, they should follow the shape of each mogul, "absorbing" as they move up a mogul and "extending" as they move down a mogul. In doing so, the pressure between their ski and the snow should remain consistent. 

Air bump: A specially constructed jump that has been set in the mogul course. 

Air score: One of the three main judging criteria. Accounts for 20% of a skier's overall score. Skiers are required to complete two airs during each mogul run. Judges evaluate each skier's aerial maneuvers based on form and difficulty. 

Backscratcher: The skier touches his back with the tails of both skis, legs together with his knees bent underneath his body and skis parallel. 

Body position: The stance, balance and movement of the competitor's body. 

Bronco: A 180-degree rotation with a spread eagle while the skier faces uphill. He then performs another 180-degree rotation to land facing downhill. 

Carving: A component of a skier's "turns" score. Refers to the technique of edging through turns down the slope to control speed. A pure carved turn is one in which the tail of the ski follows precisely the track made by the ski tip. In this scenario, there is no skidding or lateral sliding; instead, there is only minor gliding between the snow and the base of the ski. 

Control gate: A series of 10 equally spaced gates set on the mogul course. 

Cross: The crossing of the skis in an "X". 

D-Spin: An off-axis back flip with a full twist. 

Daffy: A scissor-like position in which the skier spreads his legs wide apart with one in front of the body and one behind. The front ski points straight up and the back ski points straight down. 

Double upright: The combination of two moves in one jump. 

Fall line: The shortest way down the course from the start to the finish. To avoid score deductions, skiers must stay in the selected fall line once they leave the start gate. This is a component of a skier's "turns" score. 

Form: A component of a skier's "air" score. Judges consider the quality, amplitude and fluidity of each athlete's aerial maneuvers. This includes evaluating whether a trick is performed within an acceptable axis range. 

Grab: In a jump, the competitor reaches and holds a part of the ski for a duration of time. Performing a grab results in a higher degree of difficulty. 

Four-point landing: Both poles plant when the skier lands from a jump. 

Four-point takeoff: Both poles plant as the skier takes off from the mogul. 

Helicopter: Upright aerial spin of 360 degrees. 

Heli-X: An Iron Cross executed in the middle of a helicopter, while the skier faces uphill. 

Iron cross: The ski tips are crossed while the competitor stays upright. 

Mule kick: A 90-degree drop of the skis with a 45-degree twist to the side. The tips drop but the heels are kicked out to one side. 

Off-axis: A titled rotation to one side of the vertical axis during a jump. 

Pace time: A calculated value which is different for men and ladies. To calculate the pace time take the course length in meters then divide it by the pace time value. 

Position: In a jump, the competitor can create a position, like crossing the skis, for a duration of time. Performing a position results in a higher degree of difficulty. 

Quadruple: Performing four positions during a jump. 

Quint: Performing five positions during a jump. 

Reverse trough: Technique of skiing on top of the moguls and turning in the opposite direction of the ruts. 

Ruts: The deep area between moguls. 

Speed score: One of the three main judging criteria. Accounts for 20% of a skier's overall score. This is based on the total time it takes the skier to complete their run through the course, but will be converted into a comparable point value that goes into the overall score. 

Spread: The skier's arms are extended and legs split apart to the side. The upper body remains upright with ski tips and tails even and parallel. 

Switch: Skiing backwards. Can refer to direction at the time of takeoff or landing. 

Tip cross: The ski tips cross, the competitor stays upright. 

Triple upright: A combination of three positions in one jump. 

Trough: Ruts, or a deep path through the moguls. 

Turns score: One of the three main judging criteria. Accounts for 60% of a skier's overall score. The term refers to a technical evaluation of how well a competitor turns through the moguls. This includes such considerations as fall line deviations, carving, absorption and extension. 

Twister: Skis twist 90 degrees to one side of the body, hands and body twist to the opposite side. 

With position: The addition of a position to a jump (i.e. "360 with position").

Air score: One of the three main judging criteria. Accounts for 20% of a skier's overall score. Judges evaluate the takeoff, height and distance of each skier's jump. 

Back: The direction of travel of a competitor's jump. Also known as a single flip. 

Back full: A single backflip with one full twist. 

Back layout: A single backflip in the layout position (body extended as straight as possible). 

Back somersault: A single backflip. 

Back tuck: A single backflip in the tuck position. 

Double: Two flips. 

Double full: A single layout flip with two twists. 

Double layout (or lay-lay): Two flips in the layout position. 

Double somersault: Two flips. 

Form score: One of the three main judging criteria. Accounts for 50% of a skier's overall score. Judges evaluate the position of the skier's body, skis, arm, hands and/or poles while in the air. 

Front somersault: A single forward flip. 

Front tuck: A single front flip in the tuck position. 

Full: A flip with a full twist (360 degrees). 

Full in: A full twist on the first flip of a double or triple somersault. 

Full out: A full twist on the last flip of a double or triple somersault. 

Flip: A somersault, which is either performed backwards, frontwards or sideways. 

Half: A flip with a half-twist (180 degrees). 

Half in: A half twist on the first flip of a double or triple somersault. 

Half out: A half twist on the first flip of a double or triple somersault. 

Height and distance: The arc that the competitor travels when jumping. A section of the air score. 

Kicker: The aerial jump. 

Knoll: The line that separates the table from the landing hill. 

Landing score: One of the three main judging criteria. Accounts for 30% of a skier's overall score. A proper landing involves a balanced, stable and controlled body position throughout. 

Layout (or lay): The body is extended as straight as possible during a flip. 

Loop: A side flip, where the competitor rotates around the central axis. 

Pike: The body bends at the waist, the legs remain straight. A "V" or jack-knife position. 

Puck: The body is in an open tuck position with legs pulled up 45 degrees (hands do not necessarily touch theknees). 

Pop: The extension or snap at the end of the jump which sets the flip in motion. 

Quadruple (or quad): Four flips. 

Randy: A flip with two and a half twists. 

Rudy: A flip with one and a half twists. 

Single: One flip. 

Sling: A bad takeoff from the kickers that sets a very fast rotation. Slings usually happen when a jumper throws his/her arms and shoulders back too quickly. 

Slap back: When a jumper over-rotates on landing and they go to their back before standing up and skiing out of the outrun. 

Takeoff: A good takeoff has knees, hips and arms all completely extended as a competitor's feet cross the end of the kicker. 

Table: The flat area where the jumps are built. 

Triple: Three flips. 

Tuck: The knees are pulled up in front of the body to an angle of 90 degrees from the body. 

Twist: A 360-degree spin. 

A note on aerial tricks: When aerial tricks are named, a jump with multiple flips will often be broken into a separate part for each flip. Each section describes what is happening during the course of that one particular flip. For example, a skier might attempt a "full, double full, full." This means that the first flip would have one full twist, the second flip would have two full twists, and the third flip would have one full twist. In other words, they are attempting a quadruple-twisting triple flip. 

Air time: The time from the takeoff of the jump until the landing. 

Bank: A turn that is inclined at an angle. 

Bib: Worn externally by each racer in order to identify them during competition. The color of the bibs corresponds to their qualification ranking relative to the other skiers in their heat. The red bib is assigned to the highest-ranked racer, and they are allowed to choose their lane first. 

Big final: The final round of a ski cross competition. Determines first through fourth place, including all medal positions. 

Blocking: Purposely preventing a faster competitor from passing, by turning or obstructing the line. 

Corner jump: A jump with a sharp turn on landing. 

Course design: A detailed plan of the layout of the course including the number of features, changes of direction, safety measures and finish area. 

Disqualification 1: Missing a gate, will be ranked within the round as last place. 

Disqualification 2: Will be classified as DSQ, but not ranked, caused by unsportsmanlike behaviour. 

Fall line: An imaginary line that follows the steepest gradient down a slope. (i.e the path a rolling ball would follow down the slope). 

Features: A series of natural or specially designed course elements on the course. 

Heat: Each head-to-head race during the competition is called a "heat." Each heat consists of four skiers at a time racing each other down the course. During elimination rounds, the top two skiers from each heat advance to the next round. 

Holeshot: The race to the first turn. The skier who leads the field into the first turn "gets the holeshot" and can often use it to stay in front of their competitors. 

Photo finish: The images, taken by a high speed camera, of the competitors that cross the finish line. 

Rollers: A series of gentle jumps protruding from the surface of the course. Racers must traverse over them while attempting to maintain speed, either by absorbing them or jumping through them. 

Seeding run: A time trial that determines each skier's seed for the elimination rounds. 

Small final: A consolation race featuring all skiers who did not advance out of the semifinals. Determines fifth through eighth place. 

Step-up: A jump where the landing is higher than the starting point. 

Step-down: A jump where the landing is lower than the starting point. 

Table: A jump where the landing is on the same level or a little higher than the kicker. Also called a "tabletop." 

Vertical drop: The total difference from the start elevation to the finish elevation.

Waxing: Application of substances to the base of the skis.