Idioms and Phrases with flat on one's back
flat on one's back
Sick in bed. For example, The flu has put her flat on her back.
Helpless, without recourse, defeated, as in I wish I could help but the recession has put me flat on my back.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.