(medicine) A rare neurological disorder characterized by progressive rigidity and stiffness, primarily of the axial musculature, resulting in postural deformities.

(transitive) To make stiff. / (intransitive) To become stiff.

Third-person singular simple present indicative form of stiffen

present participle of stiff

In a stiff manner.

simple past tense and past participle of stiffen

plural of stiffship

superlative form of stiff: most stiff Most rigid, most inflexible, most unbending.

comparative form of stiff: more stiff, more rigid, more inflexible, more unbending.

(slang, vulgar) An erection of the penis.