Off one's guard; unprepared: a quiz that caught the class off-guard. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "off-guard" in a sentence
"He added, "We've seen what can happen and don't want to be caught off-guard.""
"The collapse of correlations like these mean traders who relied on the connections to anticipate market movement could be caught off-guard."
"When the silken frail things float down like subliminal blossoms, and you gloat, flushed at the face, caught off-guard in the moment?"