I mean originally. I don’t mean all of the colleges, churches, hospitals, and what have you named after him/it.
Would you believe a farm? I believe it means Great Hill (actually Hill Great) in Welsh.
It was the name of the farm belonging to Rowland Ellis who was a leading Quaker in Wales. In 1686 he led a group of fellow Quakers to Pennsylvania. Once there he named a town after his old farm. Later still the famous college was named after the town.
This has a little bit about it, about 2/3s of the way down.
It might also help to realize that coal mining was (and is) a very common occupation for the Welsh, so there were probably a lot of them in Pennsylvannia at some point. There are other communities in PA with Welsh names as well (Bala Cynwyd, for instance).
Ywc y da. 
If I may be permitted a slight hijack, what does Bala Cynwyd mean? And how about Bryn Athyn?
Well, Bala is the place where a river flows out from a lake; can’t find ‘cynwyd’ in my dictionary, but it may be derived from a verb meaning to contain or to hold, so Bala Cynwyd could refer to a dam or a small reservoir.
Bryn is a hill, as has been said; again, I couldn’t find Athyn–and the construction isn’t Welsh AFAIK, so “Athyn” may be derived from addfwyn, meaning mild or weak. Mild hill? Slight hill? Gentle hill?
My best source, a native Welsh speaker, is currently celebrating the birth of his first daughter and fifth child, so he’s unavailable for me to consult right now.
Are you talking to me? You’re already out of my league. Something is or did good, but I don’t know what.
I agree with Squish on Bala and I think that Cynwyd was one of the ancient kings (possibly legendary?). So it could mean the place where a river flows out from a lake which belongs to Cynwyd.
But a quick check on the towns website indicates that it actually means that half of the founding fathers came from the town of Bala and half came from the town of Cynwyd.
I’m not familiar with Athyn either, but a check with that towns website says it means Hill of Cohesion. Sounds a lot better in Welsh though.
Ok, so Welsh. I should have realized that. . . Does this mean that the Bryn was originally pronounced something like “Broon”?
No, the ‘w’ is the long or double ‘o’–sometimes. The ‘y’ is a distinct sound something like a short ‘e’ or a short ‘i’. Bryn rhymes with grin.
is the Welsh equivalent of “cheers” (literally, “good luck”).
zigaretten is right about Athyn not being a Welsh form. The sound for “th” in Welsh is “dd” (pronounced as in “with” not “three”). Addfwyn is pronouced “athvwin,” which I suppose could be Anglocized to “Athyn.” Interestingly, when English adopted the Welsh word for poet, the “th” sound became “d.” Of course, the written change was much more minor: bardd became bard.
I’ll also consult a reasonably authoritative source; my father’s first language was Welsh.
Thanks for the help, guys. I’ll just step aside and let you continue your Welsh conversation.