: to remove the stiffness from : make limp or flexible the penetrating heat unstiffens his joints pragmatism unstiffens all our theories, limbers them up and sets each one at work— William James.

Is Unstiffened a word?

Unstiffen meaning

To remove the stiffness from; to relax; to make pliant.

What does stiffen mean in slang?

Another colloquial meaning of stiff is "to underpay, or to cheat.” Also, a stiff drink has a lot of alcohol. A dead body is sometimes called a stiff, but it's rude. Definitions of stiff.