/ Dictionary / Index S substation: Meaning and Definition of Find definitions for: sub•sta•tion Pronunciation: (sub'stā"shun), [key] — n. a branch of a main post office. an auxiliary power station where electrical current is converted, as from AC to DC, voltage is stepped up or down, etc. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: substation (Thesaurus) substantivize substituent Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language