/ Dictionary / Index A aculeus: Meaning and Definition of Find definitions for: a•cu•le•us Pronunciation: (u-ky'lē-us) [key] — pl. -le•i the modified ovipositor or sting of certain hymenopterous insects. prickle (def. 2). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: aculeus (Thesaurus) aculeate acumen Related Content Daily Word Quiz: perspicacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language