Nigh
Old English nēh, nēah, of Germanic origin; related to Dutch na, German nah . Compare with near.
wiktionary
From Middle English neygh, nygh, nye, nyȝ, from Old English nēah, nēh, from Proto-Germanic *nēhw. Cognate with Dutch na(“close, near”), German nah(“close, near, nearby”), Luxembourgish no(“nearby, near, close”). See also near.
etymonline
nigh (adv.)
"near, nearby, close together, adjacent," Middle English neigh, from Old English neah (West Saxon, Kentish), neh (Anglian), from Proto-Germanic *naehwa- (source also of Old Saxon nah, Old Frisian nei, Middle Dutch, Dutch na, Old High German nah, German nah, Gothic nehwa), of uncertain origin, with no cognates outside Germanic. The Old English progression was neah - near - niehsta, for "nigh - nigher - nighest." But the comparative near and the superlative nehst (see next) gradually evolved into separate words that were no longer felt as related to nigh. New comparative and superlative forms nigher, nighest developed 14c. as phonetic changes obscured the original relationships. As an adjective and preposition in Middle English.
