stiffen

From Middle English stifnen, equivalent to stiff +‎ -en.

• Rhymes: -ɪfən

stiffen (third-person singular simple present stiffens, present participle stiffening, simple past and past participle stiffened)

1. (transitive) To make stiff.
2. (intransitive) To become stiff.
   • 2003, Yoko Ogawa, The Housekeeper and the Professor

     Bewildered by the unexpected greeting, my son stiffened, but managed a polite answer.

• starken

• stiffen up

• stiff

• infefts