/ Dictionary / Index I instroke: Meaning and Definition of Find definitions for: in•stroke Pronunciation: (in'strōk"), [key] — n. a stroke in an inward direction. (in an engine) the stroke during which the piston moves into the cylinder. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: instroke (Thesaurus) instr. instruct Related Content Daily Word Quiz: penury Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language