Momentum stalling

Momentum stalling, also referred to as momentum halting, is a property in Super Smash Flash 2 where an aerial attack or a special move slow down a character's momentum or falling speed partially or entirely.

The vertical momentum stall, unlike the horizontal one, has a name in the game's files: air ease. It is also referred to as hit ease when applied after a move hits an opponent, though.

This property was much more prevalent in older versions of the Super Smash Flash 2 Demo, but was steadily phased out of the game, and rendered almost completely absent by v0.8a.

Momentum cancelling
Momentum canceling is a technique in the  series where a player uses a momentum halting move to cancel the momentum of an attack's knockback. When combined with Directional Influence, momentum cancelling can allow characters to survive at abnormally high percentages. It should be noted that all characters can cancel their momentum by midair jumping. Due to the absence of hitstun cancelling — like in Super Smash Bros. Brawl, momentum canceling is not as useful in SSF2 as it is in Brawl.

Momentum canceling is present in Super Smash Flash. Any attack will help decrease the amount of knockback the player has taken. It is somehow more useful in SSF than in SSF2 due to the player being able to act out of hitstun. All non-s reduce one's momentum by half.

Trivia

 * The property's names were initially coined by SSF2 Developer Starkiller and member PsnDth, via McLeodGaming's  server.