/ Dictionary / Index N NHTSA: Meaning and Definition of Find definitions for: NHTSA Pronunciation: [key] National Highway Traffic Safety Administration. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. NHS Ni Related Content Daily Word Quiz: diligent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language