According
来自Big Physics
Safin（讨论 | 贡献）2022年4月28日 (四) 10:05的版本 （建立内容为“Category:etymology == google == [https://www.google.com.hk/search?q=according+etymology&newwindow=1&hl=en ref] Old English, from Old French acorder ‘reconc…”的新页面）
Old English, from Old French acorder ‘reconcile, be of one mind’, from Latin ad- ‘to’ + cor, cord- ‘heart’; influenced by concord.
wiktionary
accord + -ing
etymonline
according (adj./adv.)
c. 1300, "matching, similar, corresponding" (a sense now obsolete), present-participle adjective and adverb from accord (v.). Meanings "conforming (to), compliant, in agreement; consistent, harmonious; suitable, appropriate" are from late 14c. According to "referring to," literally "in a manner agreeing with" is from late 14c. As an adverb, "often applied to persons, but referring elliptically to their statements or opinions" [Century Dictionary].
