Partially raised or lowered. The phrase most often describes a flag that has been lowered to honor a recently-deceased person. After our former president died, flags were at half-mast all across the country. My daughter came home from the park covered in dirt, her ponytail at half-mast.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
at half-mastand at half-staff
[of a flag] halfway up or down its flagpole. The flag was flying at half-mast because the general had died. Americans fly flags at half-staff on Memorial Day.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
Halfway up or down, as in The church bells tolled off and on all day and the flags were at half-mast. This term refers to placing a flag halfway up a ship's mast or flagpole, a practice used as a mark of respect for a person who has died or, at sea, as a distress signal. Occasionally the term is transferred to other objects, as in Tom's pants were at half-mast as he raced around the playground, or The puppy's tail was at half-mast. [First half of 1600s]
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.