Etymology

The first recorded use of the term "brass monkey" appears to dates to 1857 when it was used in an apparently vulgar context by C.A. Abbey in his book Before the Mast, where on page 108 it says "It would freeze the tail off a brass monkey." [Source: Lighter, J.E. ed. Random House Historical Dictionary of American Slang. (New York: Random House, 1994): 262.].

• False etymologies debunked

  brass monkey in Wikipedia

  http://www.snopes.com/language/stories/brass.htm SPAM debunking from Snopes

  http://www.history.navy.mil/faqs/faq107.htm Naval Historic Society's SPAM Rebuttal

Adjective

1. said of the weather when it is very cold.

   It's brass monkey weather today, isn't it?

2. a cocktail of vodka, rum and orange juice, sometimes with the addition of galliano
3. a kind of inexpensive liqueur
4. an Australian beer