A picture you can hold: a gate with a line drawn across it. Whoever or whatever stands at that gate decides what may pass and how far it may go. A runner who gets through the gate is a qualifier. The race that holds the gate is also a qualifier. And a small word such as very or const stands beside a bigger word and draws the same kind of line, saying how far that word is allowed to reach. In every use, the word names the thing that sets the condition — not the prize on the other side.
From the word’s history
Wiktionary's entry gives the word as qualify + -er: the one that qualifies. That fits the modern uses, where the word names the person, event or word that meets or sets a condition.
來源把這個字拆成 qualify 加上 -er，也就是「做 qualify 這件事的人或東西」。qualify 本身有兩條線：一條是「達到標準」，一條是「加上條件、限定住」。今天 qualifier 的四個用法，剛好分別長在這兩條線上。
Wiktionary (kaikki extract) entry for 'qualifier', etymology_text: 'From qualify + -er.'
登入就可以看每一支怎麼連回核心畫面。