From Middle English ter, terr, tarr, from Old English teoru, from Proto-West Germanic *teru, from Proto-Germanic *terwą (compare Saterland Frisian Taar, West Frisian tarre, tar, Dutch teer, German Teer), from Proto-Indo-European *derwo- (compare Welsh derw ("oaks"), Lithuanian dervà ("pinewood, resin"), Russian де́рево ("tree"), Bulgarian дърво́ ("tree")), from *dóru. More at tree.