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crack up - definition and synonyms

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phrasal verb informal
Word Forms
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present tense
I/you/we/theycrack up
he/she/itcracks up
present participlecracking up
past tensecracked up
past participlecracked up
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  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

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an ancient Roman system of underfloor heating, used to heat houses with hot air; from the Latin 'hypocaustum'

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