flat as a tack

(as) flat as a tack

Demoralized or unenergetic. She's been flat as a tack ever since she heard that she didn't get into her top choice school.
See also: flat, tack
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

flat as a tack

in very low spirits or lacking in energy. informal
The idea underlying the expression is of a tack that has been hammered in so that none of it protrudes.
See also: flat, tack
Farlex Partner Idioms Dictionary © Farlex 2017
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