/ Dictionary / Index K km/sec: Meaning and Definition of Find definitions for: km/sec Pronunciation: [key] kilometers per second. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. K meson KN Related Content Daily Word Quiz: designate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language