Meaning

noun a groove or furrow (especially one in soft earth caused by wheels)

noun a settled and monotonous routine that is hard to escape

noun applies to nonhuman mammals: a state or period of heightened sexual arousal and activity

originFrom Middle English rutte (noun) and rutten (verb), from Old French rut (“noise, roar, bellowing”), from Latin rugītus, from rugīre (“to roar”).

Etymology from Wiktionary, CC BY-SA 3.0