核心畫面
Think of a lid and a jar: the lid fits, so it can do the job. Fitness can be thought of as that matching — how well something measures up to what a job actually asks for. The gym sense sits inside the same picture: a fit body is a body that measures up to what running, lifting or a long day of work demands of it.
可以想成蓋子跟罐子：蓋得上，才能派上用場。fitness 就像是在問「合不合得上」——這個人、這樣東西，撐不撐得起那…更多收起
可以想成蓋子跟罐子：蓋得上，才能派上用場。fitness 就像是在問「合不合得上」——這個人、這樣東西，撐不撐得起那件事的要求。健身房那個意思其實還在同一張圖裡：體能好，就是身體對得上跑步、搬東西、上一整天班對它提出的要求。這也是為什麼「健身」跟「適任」會是同一個字。From the word’s history
Fitness first meant 'the state or quality of being suitable' (1570s), from the adjective fit 'suited to the circumstances, proper' (mid-15c.) + -ness. Fit only took on the athletic sense 'in condition, properly trained for action' by 1869, and fitness in the sense 'state of being physically fit' is recorded from 1935 — so the health meaning is a late branch off the older idea of measuring up to what is required.
fitness 最早（1570 年代）就是「適合、恰當」的意思，由形容詞 fit（15 世紀中，「合乎情況的、恰當的」）加字尾 -ness 造成。fit 一直到 1869 年才出現運動上「狀態好、練到可以上場」的用法，而 fitness 指「身體狀況好」更晚到 1935 年才有紀錄。所以「體能」是從比較老的「合得上要求」那個意思後來長出來的一支。
Online Etymology Dictionary (etymonline.com), entries 'fitness' and 'fit (adj.)'
原始詞典資料4 筆記錄
以下是外部詞典記錄的用法，原文照列，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。
fitnessnoun/ˈfɪt.nəs/
- 1
The condition of being fit, suitable or appropriate.
- Having introduced my two characters separately, let me present them together. Why not? He, young, wealthy, honorable; she also young, also intelligent — why not bring them together? There is an eternal fitness in all things, and nothing more so than in the case of man and woman.
- That's chiefly why they're coming; I want you to meet them here and then tell me frankly what you think of their fitness for whatever we decide on doing.
- 2
The cultivation of an attractive and/or healthy physique.
- Carroll has been edging slowly towards full fitness after his expensive arrival from Newcastle United and his partnership with £23m Luis Suarez showed rich promise as Liverpool controlled affairs from start to finish.
- 3
An organism's or species' degree of success in finding a mate and producing offspring.
- 4
slangThe condition of being attractive, fanciable or beautiful.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。