/ Dictionary / Index P proctodeum: Meaning and Definition of Find definitions for: proc•to•de•um Pronunciation: (prok"tu-dē'um), [key] — pl. -de•a -de•ums. a depression in the ectoderm of the anal region of a young embryo, which develops into part of the anal canal. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. proctodaeum proctology Related Content Daily Word Quiz: pristine Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language