v (intransitive) To propel oneself rapidly upward such that momentum causes the body to become airborne.
v (intransitive) To react to a sudden, often unexpected, stimulus (such as a sharp prick or a loud sound) by jerking the body violently.
v (intransitive) To employ a move in certain board games where one game piece is moved from one legal position to another passing over the position of another piece.
v (transitive) To increase the height of a tower crane by inserting a section at the base of the tower and jacking up everything above it.
n A button (of a joypad, joystick or similar device) whose only or main current function is that when it is pressed it causes a video game character to jump (propel itself upwards).
n (sports|horses) An obstacle that forms part of a showjumping course, and that the horse has to jump over cleanly.
n (mathematics) A discontinuity in the graph of a function, where the function is continuous in a punctured interval of the discontinuity.