crack up

• Audio (AU)

  (file)

crack up (third-person singular simple present cracks up, present participle cracking up, simple past and past participle cracked up)

1. (idiomatic, intransitive) To laugh heartily.

   It was hilarious. We were cracking up the whole time.

2. (idiomatic, transitive) To cause to laugh heartily.

   The joke about the nuns in the bath cracked me up.

3. (intransitive, idiomatic) To become insane; to suffer a mental breakdown.

   She got through the war, but cracked up when her sister died.

4. (transitive, informal, usually passive, usually negative) To cry up; to extol.

   The job just can't be all that she 's cracked it up to be.

   It is not necessarily the great thing that the proponents are cracking it up to be.

   This new computer system is not what it was cracked up to be.

   It not nearly as good as it has been cracked up to be.

   I wonder whether it could be all it is being cracked up to be.

5. (of an aircraft or automobile) To crash.
   • 1930, Lawrence M. Guyer, "Chuck Luck: The Story of a Flying Dog" (Boys' Life, December 1930)

     From all directions they came to the rescue, one predominant fear gripping their hearts: Fire! Someone had cracked-up. It was for this they sped. The flames that so frequently burst from a crashed airplane became an instantaneous cauldron; many a pilot has lived through the crash to die in the fire that followed.

• crack up at OneLook Dictionary Search
• crack in The Century Dictionary, New York, N.Y.: The Century Co., 1911.