veretilla

Etymology
From.

As it is first attested in Apuleius, it may have been a neologism coined by him, possibly intended as a translation of Greek, to refer to a type of shellfish that visually resembled a human penis.

Editors differ on whether the passage where this word occurs should be read with feminine singular accusative "veretillam" or neuter singular accusative "veretillum", or even neuter plural accusative "veretilla". If the feminine form "veretillam" is correct, there is a change in gender from the neuter base word. In principle, such gender changes may proceed by means of mistaking neuter plural forms such as verētra/verētilla for nominative feminine singular forms; however, per Adams, was generally used in the singular, unlike similar euphemisms such as verenda, verendōrum, so this may be a less likely route of gender change for this word than for others.

The vocalism in -ill- is uncommon for a diminutive built on a -ro-stem noun with assimilation of -rl- to -ll-: the expected formation would be in -ell-. Strodach suggests the form was possibly influenced by analogy with a diminutive, from in the meaning "penis".

Usage notes
The gender and declension of this word is uncertain (see "Etymology" above) due to different editorial interpretations of the form found in Apuleius. Thus, the true form might instead be neuter.