caterpillar
cat.er.pil.lar \'kat-*(r)-.pil-*r\ n [ME catyrpel, fr. ONF catepelose, lit., hairy cat] often attrib : the elongated wormlike larva of a butterfly or moth; also : any of various similar larvaeCaterpillar tm : - used for a tractor made for use on rough or soft ground and moved o n two endless metal belts