go off

go off idiom
  1. Explode, detonate; also, make noise, sound, especially abruptly. For example, I heard the gun go off, or The sirens went off at noon. This expression developed in the late 1500s and gave rise about 1700 to the related go off half-cocked, now meaning “to act prematurely” but originally referring to the slipping of a gun's hammer so that the gun fires (goes off) unexpectedly.
  2. Leave, depart, especially suddenly, as in Don't go off mad, or They went off without saying goodbye. [c. 1600]
  3. Keep to the expected plan or course of events, succeed, as in The project went off smoothly. [Second half of 1700s]
  4. Deteriorate in quality, as in This milk seems to have gone off. [Late 1600s]
  5. Die. Shakespeare used this sense in Macbeth (5:9): “I would the friends we missed were safely arrived.—Some must go off.”
  6. Experience orgasm. D.H. Lawrence used this slangy sense in Lady Chatterley's Lover (1928): “You couldn't go off at the same time....” This usage is probably rare today. Also see get off, def. 8.
  7. go off on a tangent. See under on a tangent.
  8. go off one's head. See off one's head. Also see subsequent idioms beginning with go off.

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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