/ Dictionary / Index S senior high school: Meaning and Definition of Find definitions for: sen'ior high' school" Pronunciation: [key] a school attended after junior high school and usually consisting of grades 10 through 12. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. senior citizen seniority 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