ie = (4) Upper German iu (OHG. io) before labials and gutturals, as liup, dear, tiuf, deep, siuch, sick, liugen, to tell a lie = liep, tief, siech, liegen.
öu (eu) is the umlaut of OHG. ou, as löuber, leaves, löufel, runner = OHG. loubir, loufil.
üe is the umlaut of OHG. uo, as grüene, green, güete, goodness, vüere, thou didst go = OHG. gruoni, guotī, fuori.
Unaccented Vowels and Umlaut.
[§ 6.] The two most characteristic differences between OHG. and MHG. are: (1) the spread of umlaut ([§ 10]); (2) the weakening and partial loss of vowels in unaccented syllables.
1. The Weakening of Unaccented Vowels.
[§ 7.] The short vowels a, i, o, u, and the long vowels ē, ī, ō, ū were weakened to e. This e was pronounced like the final -e in NHG. leute, see [§ 3]. Examples are:—
gëba, gift, hërza, heart, zunga, tongue, taga, days = MHG. gëbe, hërze, zunge, tage; heilag, holy, neut. blindaȥ, blind, nëman, to take = MHG. heilec, blindeȥ, nëmen.
kunni, race, generation, gesti, guests = MHG. künne, geste; kuning, king, beȥȥisto, best, dat. pl. gestim, to guests, gen. pl. lembiro, of lambs, nimit, he takes = MHG. künec, beȥȥest (beste), gesten, lember(e), nimet.
haso, hare, nom. acc. pl. fem. blinto, blind, gen. pl. tago, of days = MHG. hase, blinde, tage; acc. sing. hason, hare = MHG. hasen.