and, thanks to fourwind, because I did print off the Etymology of British Place names;
Tre(Cymric) a village, a house;egTrefriw, treton.
Tri " three; eg. Tryfan (three-headed), Truro
Tuaim (gaelic) a tumulus, Tuam, toome, Tomgrany. It also says see Tom but I am not going to type the whole dictionary, its on the net.......