David Chess of the very readable Chess Log writes (at the bottom of a long entry):
Placename o’ the day: “Torpenhow Hill”. “Tor”, “Pen”, and “Howe” all mean “Hill”, so the name means “Hill Hill Hill Hill”. *8)
Tor, pen, and howe aren’t exact synonyms. A tor is a specific geographic feature, a high peaked hill, Glastonbury Tor is the best known one. Torpenhow is a village in Cumbria, set on a high hill. Tor is often used to refer to a rocky outcrop on top of a hill, and it’s not unusual for the outcrop to really be a pile of stones put there in earlier times. The American Heritage Dictionary entry for tor suggests that Old English torr may be a Celtic loan word. The second edition of the OED etymology for tor offers Welsh twr, with a grave over the w, Old Welsh twrr “heap, pile” as in Mynydd Twrr, the old name of Holyhead Mountain, Rhys [with a circumflex over y]. The OED adds that tor is likely cognate with Gaelic tòrr “hill of an abrupt or conical form, lofty hill, eminence, mound, grave, heap of ruins.” The entry points to related words in Irish, namely tòrr “to heap up, pile up, bury,” torraim “I heap up,” and the Scots Gaelic derivative, torran “little hill, knoll, hillock,” Irish torrán “heap, pile, hillock.”
Howe is derived from Old Norse haug-r, “mound, cairn,” and, according to the second edition of the OED, is related to Old Teutonic hauh– meaning “high.” The word howe in English is usually used to refer to an artificial hill, a tumulus, or barrow.
Pen is Welsh, and it usually means not hill but “head.” It’s cognate with Gaelic “cen,” which also means head. (Those of you who wish to mind your Ps and Qs, or P-Celtic and Q-Celtic languages might want to read this FAQ on the Celtic languages.) The OED describes it as a Brythonic Celtic word
frequent in place names in Cornwall, Wales, and other parts of Britain, as Penzance, Penmaenmawr, Penrith, Pencaitland; in some localities, esp. in the south of Scotland, used as a separate word in names of hills, e.g. Eskdalemuir Pen, Ettrick Pen, Lee Pen, Penchrise Pen, Skelfhill Pen, etc.; rarely as common noun, “the pen”.
Pen, in Welsh, also means “top” or even “chief, supreme” as in the Welsh title of the first branch or tale of the mabinogi, Pwyll Pendeuic Dyuet, wherein the first line tells us “Pwyll Pendeuic Dyuet a oed yn arglwyd ar seith cantref Dyuet,” Pwyll, chief [or prince] of Dyfed, was lord of the seven cantrefs of Dyfed.”
What we have then in Torpenhow is not just the use of three words meaning “hill” in three languages once used in Britain, but three words for special kinds of hills, hills that are marked by being artificially created, as barrows, homes for the dead, or that are marked by stones as somehow important, hills that stand out. The curious accident of speakers of all three language finding the hill name worthy is enough to make one wonder why. I am reminded of the Welsh word gorsedd, cognate with Irish síd, hills that have close associations with the otherworld, so much so that the fairy hills in Ireland have lent their name to their inhabitants, the Sidhe. At the same time, it may simply be that the hill was a very visible and thus easily identifiable landmark, much like the Abenaki word for such small stand-alone mountains, Monadnock, known to geologists as an inselberg.