stiff as a board

(as) stiff as a board

Very straight, rigid, or inflexible. Used to describe someone's physical posture or demeanor. The whole class sat in their chairs as stiff as boards during the principal's lecture. He stood as stiff as a board after his name was called, too nervous move.
See also: board, stiff

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.
See also: board, stiff

stiff as a board

If you or your body are as stiff as a board, you are very stiff. You'll achieve flexibility very quickly with these exercises — even if you're as stiff as a board at your first session. His lower back felt as stiff as a board.
See also: board, stiff

(as) stiff as a ˈboard

(of things) very firm and difficult to bend or move: He left his gloves outside in the snow, and when he found them again they were as stiff as a board.
See also: board, stiff