: 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 Unstiffen a word?

Unstiffen meaning

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

What is the meaning of unvaccinated?

: not having received a vaccine : not vaccinated children unvaccinated for measles.