Vowel Changes: Syncope and Semi-vowel changes
Syncope and semivowel deletion As a rule, syncope occurs in unstressed syllables. However, the rules for its operation within the unstressed syllables are not easy to define. Syncope tends to occur in words which in the proto-language were trisyllabic (or longer). However, it is reflected in by no means a regular way, cf. jo˛tn-ar ‘giants’ (nom. pl.; 2 syllables) -- *jo˛t-un-ar (3 syllables), but skrif-ar-ar ‘scribes’ (3 syllables). Syncope is quite irregular among adjectives, operating in some words, and not operating in others, even though they may belong to the same derivational type, cf. mál-igr ‘talkative’ – acc. sg. masc. málgan, but kunn-igr ‘expert’ – acc. sg. masc. kunnigan. It always occurs in nouns ending in -ull, cf. from jo˛k-ull ‘glacier’, djo˛f-ull ‘devil’ (nom. sg.) – jo˛kl-ar, djo˛fl-ar (nom. pl.), but never in adjectives with the same ending, cf. gjo˛f-ull ‘generous’ – acc. sg. masc. gjo˛f-ulan. It also systematically occurs in the genitive plural of nouns ending in -inn and -ann, cf. him-inn ‘sky’, apt-ann ‘evening’ – himn-a, aptn-a (gen. pl.), but never in adjectives/participles ending in -inn, cf. fund-inn ‘found’ – fund-inna, etc.
The semivowels /j/ and /v/ are deleted before front resp. rounded vowels, cf. vili ‘will’ (nom. sg.; -- [virtual] *vilji) vs. vilja ‘id.’ (obl.), also so˛ngum ‘songs’ (dat. pl.; -- [virtual] *sangvum) vs. so˛ngvar ‘id.’ (nom. pl.). These phenomena are usually found among ja/jō- and wa/wō- nominal stems, but sometimes can also be observed in the verb system.