present participle of muff

(slang) Penetration of the inguinal canal (e.g. with a finger, or by pushing the testicle back inside it) as a form of sexual activity among trans women.

simple past tense and past participle of muff

Wearing a muff.

Initialism of maximum usable frequency. / (nuclear energy) Initialism of material unaccounted for.

plural of MUF