*-gin

Probably from a Proto-Northwest Germanic suffix, *-gin, from an earlier postposed clitic *-kʷena, from Proto-Indo-European*kʷe-na, the formally and semantically weakened clitic counterpart of *kʷó-na. The latter was a modal or instrumental adverbial derivative of the PIE interrogative-indefinite stem *kʷó-/*kʷí-, formed with the fossilized adverbial ending *-na (Dunkel 2014: 481–84). The voiced *g is from Verner’s Law due to early cliticization. The *i is from raising of *e before a tautosyllabic nasal after reduction of the clitic to a closed syllable, i.e. *-gʷen/*-gen > *-gin; unreduced *-gʷena would not itself have triggered this raising (Fulk 2018: 57; Ringe 2017: 173–74). Cognates include Vedic Sanskrit चन (caná) and Avestan 𐬗𐬌𐬥𐬁 (cinā), continuing Indo-Iranian *čana < PIE *kʷena. (Dunkel 2014: 482–84). The Gothic suffix -𐌷𐌿𐌽 (-hun) is functionally parallel, especially in negative expressions, but formally distinct. It continues PIE *ku-na, from the local/interrogative particle *kú.