Meaning

noun a definite length of time marked off by two instants

noun a set containing all points (or all real numbers) between two given endpoints

noun the distance between things

originFrom Middle English interval, intervalle, from Old French intervalle, entreval, from Latin intervallum (“space between, interval, distance, interval of time, pause, difference; literally, space between two palisades or walls”), from inter (“between”) + vallum (“palisade, wall”).

Etymology from Wiktionary, CC BY-SA 3.0