/ Dictionary / Index S senile dementia: Meaning and Definition of Find definitions for: se'nile demen'tia Pronunciation: [key] — Pathol. Pathol. a syndrome of progressive, irreversible impairment of cognitive function, caused by organic factors and having its onset late in life. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. senile senile macular degeneration Related Content Daily Word Quiz: neologism Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language