Its source is an Old English expression meaning "Hill."
This surname might have designated a person who lived or worked around a sheep pen.
Its use as a first name in the U.S. is probably due to admiration for the Quaker leader William Penn (1644-1718). The son of an influential English family, he forsook the comforts of a genteel life to found Pennsylvania (in Latin, ''Penn's woods''). It was one of the thirteen original English colonies in North America, and a haven of true religious tolerance.