Observer
来自Big Physics
Safin（讨论 | 贡献）2022年4月27日 (三) 01:53的版本 （建立内容为“Category:etymology == wiktionary == [https://en.wiktionary.org/wiki/observer ref] From observe + -er. == etymonline == [https://www.etymonline.com/wo…”的新页面）
wiktionary
From observe + -er.
etymonline
observer (n.)
1550s, "one who keeps a rule, custom, etc.," agent noun from observe. Meaning "one who watches and takes notice" is from 1580s; this is the sense of the word in many newspaper names. Meaning "one who observes without participating" (at a meeting, conference, etc.) is by 1925.
