sit up - definition and synonyms

phrasal verb
present tense
I/you/we/theysit up
he/she/itsits up
present participlesitting up
past tensesat up
past participlesat up
  1. 1
    [intransitive/transitive] to go from a lying position to a sitting position, or to help someone to do this

    Would you like to sit up and read for a while?

    We sat her up in a chair.

  2. 2
    [intransitive] to sit straight and not bend or lean
    sit up straight:

    You’ve got to stop slouching and sit up straight.

  3. 3
    [intransitive] British to go to bed later than usual

    We sat up very late talking last night.

See also main entry: sit