One way to picture it: the thing that gets done every time, because that's how it has always been done here — a groove worn into behaviour by , not a written rule.
From the word’s history
From Middle English custumary, from Medieval Latin custumarius, on custom + -ary — literally "belonging to custom", i.e. to what is repeatedly done.
這個字來自中古英語 custumary、再往上是中世紀拉丁文 custumarius，拆開就是 custom（習俗、慣例）加 -ary（屬於…的）——字面即「屬於慣例的」。所以只要記得 custom 這個字，customary 的兩個用法都能推出來：屬於「一群人的慣例」，或屬於「某個人的慣例」。
Wiktionary, entry "customary" (Middle English custumary < Medieval Latin custumarius; custom + -ary)
登入就可以看每一支怎麼連回核心畫面。
原始詞典資料3 筆記錄
以下是外部詞典記錄的用法，摘錄並精簡格式，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
customaryadj/ˈkʌs.tə.m(ə.)ɹi/
- 1
In accordance with, or established by, custom or common usage.
- At half-past nine on this Saturday evening, the parlour of the Salutation Inn, High Holborn, contained most of its customary visitors.[…]In former days every tavern of repute kept such a room for its own select circle, a club, or society, of habitués, who met every evening, for a pipe and a cheerful glass.
- When two people met for the first time in Diaspar—or even for the hundredth—it was customary to spend an hour or so in an exchange or courtesies before getting down to business, if any.
- 2
Holding or held by custom.
- customary tenants
- The tenants are chiefly customary and heriotable.
customarynoun/ˈkʌs.tə.m(ə.)ɹi/
- 1
lawA book containing laws and usages, or customs; a custumal.
摘錄自 英文維基詞典 English Wiktionary，已精簡格式；依 CC BY-SA 4.0 授權使用，改動後的內容同樣以此授權提供。