身體上的口
這一支離「嘴」的畫面最近：真正的嘴，加上跟嘴同一類的鼻孔、耳朵。
noun · C1
One of the natural openings in the body of a person or an animal, such as the mouth, the nose, or the ears.
身體的孔口
核心畫面
One way to hold this word is to keep a mouth in mind. Not a hole punched through something, but an opening that is made to be an opening — something is supposed to go in or come out of it. The nose, the ears, the end of a pipe, the tiny points in a shower head, the dark gap at the bottom of a cliff: all of them are places with a rim, and a way through. English keeps this word for careful writing, so when you meet it the writer is usually being exact rather than being colourful.
一種記法是把它想成一張嘴。不是被打穿的洞，而是本來就要讓東西進出的口。鼻孔、耳朵、管子的兩端、蓮蓬頭上的小孔、懸崖底…更多收起
一種記法是把它想成一張嘴。不是被打穿的洞，而是本來就要讓東西進出的口。鼻孔、耳朵、管子的兩端、蓮蓬頭上的小孔、懸崖底下那道黑黑的縫，都有一圈邊，也都有一條通路。英文把這個字留給比較正式的場合，所以看到它，多半代表作者想講得精確，而不是想講得生動。From the word’s history
Recorded as coming through Middle French and Old French from Late Latin orificium, literally 'the making of a mouth', from os (mouth) plus facio (to make).
依據來源，這個字經由中古法文、古法文，回到後期拉丁文 ōrificium，字面就是「做出一張嘴」：ōs（嘴）加上 faciō（做）。這條線索剛好說明為什麼身體上的孔和管子的口共用同一個字。
Wiktionary entry supplied in this packet (source_ref kaikki:3f6f69a190036ae4:526409816:17653): 'From Middle French, from Old French, from Late Latin orificium (an opening, literally the making of a mouth), compound of os (mouth) + facio (to make).'
Two branches
器物上的口
同一個「嘴」的畫面搬到東西上；這是用法上的延伸，不是在說哪一個意思比較早出現。
noun · C1
An opening or hole in a thing, especially the mouth of a tube, a pipe, or another narrow passage that something goes into or comes out of.
開口、孔