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stiff as a board

Also, stiff as a poker. Inflexible, rigidly formal, unbending, as in This cloth is stiff as a board; what happened to it? or There he stood, stiff as a poker, unwilling to give an inch. The board in the first simile for rigidity is a slab of wood; the second, alluding to the iron implement used to push around logs in open fires, dates from the late 1700s.

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RELATED WORDS

solid, stark, tight, tense, rigid, thick, wooden, creaky, arthritic, firm, refractory, set, brittle, rheumatic, buckram, fixed, frozen, graceless, hardened, inelastic
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.