Triadelphia is a town in Ohio County, West Virginia, United States. It is part of the Wheeling, West Virginia Metropolitan Statistical Area. The population was 817 at the 2000 census. Triadelphia was originally chartered in 1829. Name adopted from the Greek word meaning three brothers, and probably named for the three sons of Colonel Josias Thompson, who donated the land upon which the town was originally laid out. It is home to the Highlands, the largest retail complex in the Northern Panhandle of West Virginia.