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1. A stomach exercise in which a person sits up from a supine position without using the arms for leverage

1. Not go to bed
   "We sat up all night to watch the election"
   - stay up
    
2. Change to an upright sitting position
   "He sat up in bed"

Derived forms: sit-ups, sitting up, sat up, sits up

Type of: change posture, stomach exercise, tummy crunch, wake

Encyclopedia: Sit up