- an exercise in which a person lies flat on the back, lifts the torso to a sitting position, and then lies flat again without changing the position of the legs: formerly done with the legs straight but now usually done with the knees bent.
- to raise (oneself or another) from a recumbent to an upright or alert sitting posture
- to remain out of bed and awake, esp until a late hour
- to become suddenly interested or alert
- a physical exercise in which the body is brought into a sitting position from one lying on the back
