crack up - definition and synonyms

phrasal verb informal
present tense
I/you/we/theycrack up
he/she/itcracks up
present participlecracking up
past tensecracked up
past participlecracked up
  1. 1
    [intransitive] to become mentally ill

    He just cracked up from the stress.

  2. 2
    [intransitive] to suddenly laugh a lot at something

    The girls all cracked up when they saw him.

    1. a.
      [transitive] crack someone up to make someone laugh a lot

      Little kids just crack me up with the things they say.

  3. 3
    something is not all it’s cracked up to be used for saying that something is not as good as people say that it is
See also main entry: crack