Thread:User talk:CodeCat/Appendix:Proto-Germanic/kelþan/reply

I'm not actually quite sure. I found the reference to it being an a-stem on etymonline.com, but we'd need an Old English editor to confirm it. The change lþ > ld is regular for West Germanic, there are other words like gold where it happened too. I'm not actually sure about the stem vowel, but if is a cognate, the stem vowel must have been -e- unless it was umlauted to -i-. It could only have been -i- if the stem originally had -y- in it, i.e. e-grade -ey- (> -ī-), zero grade -i-. But must be a zero-grade kulþ-, so the e-grade must be kelþ-. lþ is also the only possible etymology for West Germanic ld paired with North Germanic ll, because a Germanic ld would have become ld in North Germanic also. And then there is Gothic.