- "there are way too many penii in here"
penii
plural; back formation
the (incorrect) plural form of penis - incorrectly assumed to be a Greek word, in which the plural form of -us is -i. The actual plural form of the Latin word penis is penises or penes.
Etymology : 'peni'(s) (Latin word for tail) + '-i' (Greek plural modifier)
Source : overheard at a party
Last modified: 3 December 2008