Nine
Old English nigon, of Germanic origin; related to Dutch negen and German neun, from an Indo-European root shared by Sanskrit nava, Latin novem, and Greek ennea .
wiktionary
From Middle English nyne, nine, from Old English nigon, from Proto-West Germanic *neun, from Proto-Germanic *newun, from Proto-Indo-European *h₁néwn̥.
etymonline
nine (adj., n.)
"the cardinal number one more than eight or one less than ten; the number which is one more than eight;" Middle English nīn, from Old English nigen, from Proto-Germanic *newun (source also of Old Saxon nigun, Old Frisian niugun, Old Norse niu, Swedish nio, Middle Dutch neghen, Dutch negen, Old High German niun, German neun, Gothic niun "nine").
This is from PIE root *newn "nine" (source also of Sanskrit nava, Avestan nava, Greek ennea (with unetymological initial e-), Albanian nende, Latin novem (with change of -n- to -m- by analogy of septem, decem), Lithuanian devyni, Old Church Slavonic deveti (the Balto-Slavic forms by dissimilation of -n- to -d-), Old Irish noin, Welsh naw).
As "a symbol representing the number nine," late 14c. The proverbial nine lives of a cat are attested from 17c. Nine-to-five "the average workday" is attested from 1935. Nine days (or nights) has been proverbial since mid-14c. for the time which a wonder or novelty holds attention; the expression nine days' wonder is from 1590s. The Nine "the Muses" is from c. 1600. Also see nines.
