rut Rut [M16th] in the sense of a furrow in a road is of uncertain origin but may be from Old French rute, also the source of route [ME] which both go back to Latin rupta (via) ‘broken (way)’. Route is also the origin of routine [M17th] for something that is like travelling the same road again. Rupta is the source of rout [L16th] for a decisive defeat, from the idea of a broken army. The rut [LME] of male deer is a different word. In the breeding season stags challenge one another by roaring calls, and rut probably comes from Latin rugire ‘to roar’ (see also rail).