day off - Phrases/Idioms
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.
A day away from work, school, or a similar obligation; a free day. For example, Sophie always used her day off to do errands. [Late 1800s]