Ninth
来自Big Physics
wiktionary
From Middle English nynthe, nynte, from Old English niġoþa, from Proto-Germanic *newundô; the -n- was reinserted by analogy with nine.
etymonline
ninth (adj., n.)
"next in order or rank after the eighth; being one of nine equal parts into which a whole is regarded as divided;" c. 1300, nynþe, an alteration or replacement (by influence of nine) of nigonðe, from Old English nigoða, nigend. As a noun, "ordinal numeral corresponding to nine," late 13c. As the name of a musical interval, 1590s. Related: Ninthly.
