Definitions
1.VerbTo enter something quickly, usually a mode of transport."I jumped in the car, and we sped off to the meeting."
2.VerbTo join in on an activity quickly.
3.VerbTo interrupt someone while they are speaking.
4.VerbTo initiate into an organization, usually a gang, with violence.
5.VerbTo play a card that matches the top card in the discard pile out of turn.
6.VerbUsed other than figuratively or idiomatically: see jump, in.
7.VerbTo ambush (someone).