/ Dictionary / Index M mammillaria: Meaning and Definition of Find definitions for: mam•mil•lar•i•a Pronunciation: (mam"u-lâr'ē-u), [key] — n. any of various cacti of the genus Mammillaria, including the pincushion cactus. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: mammillaria (Thesaurus) mammilla mammillary Related Content Daily Word Quiz: placid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language