Newbie Silencer
An attack whiffs when it fails to come into physical contact with the opponent. If it didn't hit and wasn't GIed or guarded, it whiffed. Whiffs often occur because the attack came from too far away or the opponent sidestepped, but there can be other reasons.
A stun is shakeable if you can recover from it quicker by inputting a number of directions (usually 5) than by not putting in those directions. Most shakeable stuns will leave you standing after recovery if opponent doesnt hit you while true stuns usually leave you downed on the ground, but there are exceptions.
Whiff punishment is when an opponent's attack whiffs and you hit them before they recover. Block Punishment, also just sometimes called punishment, is when an attack is blocked that leaves the opponent open to retaliation with no ability to prevent it and such a retaliation ensues. Whether an attack can be block punished depends on the attack itself and what attacks the blocking character has at their disposal.
Teching (or as the game calls it "ukemi") is a quick get up that can be performed after the knockdown caused by some attacks or after being hit while grounded. In these situations one presses guard and possibly a direction and springs to their feet quickly. In the process however there is a window where the character is considered by the game standing, but unable to block. A tech trap is landing an inescapable hit on someone because they teched, generally by hitting someone in the aforementioned window.
