Definition of "Rut" :

noun: a settled and monotonous routine that is hard to escape

"They fell into a conversational rut."

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

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

verb: hollow out in the form of a furrow or groove

verb: be in a state of sexual excitement; of male mammals