Old English weorþ "significant, valuable, of value; valued, appreciated, highly thought-of, deserving, meriting; honorable, noble, of high rank; suitable for, proper, fit, capable," from Proto-Germanic *wertha- "toward, opposite," hence "equivalent, worth" (source also of Old Frisian werth, Old Norse verðr, Dutch waard, Old High German werd, German wert, Gothic wairþs "worth, worthy"), which is of uncertain origin. Perhaps a derivative of PIE *wert- "to turn, wind," from root *wer- (2) "to turn, bend." Old Church Slavonic vredu, Lithuanian vertas "worth" are considered to be Germanic loan-words. From c. 1200 as "equivalent to, of the value of, valued at; having importance equal to; equal in power to."
as final element in place names (and thence surnames), from Old English worþ "enclosed place, homestead." Also -worthy (Old English worþig).