Normal's
来自Big Physics
Safin（讨论 | 贡献）2022年4月29日 (五) 04:14的版本 （建立内容为“Category:etymology == google == [https://www.google.com.hk/search?q=normal's+etymology&newwindow=1&hl=en ref] mid 17th century (in the sense ‘right-angled…”的新页面）
mid 17th century (in the sense ‘right-angled’): from Latin normalis, from norma ‘carpenter's square’ (see norm). Current senses date from the early 19th century.
