Available for immediate use, as in Umbrellas at the ready, we were prepared to brave the storm. This idiom was originally a military term in which the ready denoted the position of a firearm prepared to be raised and aimed or fired. [First half of 1800s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.