capital (adj.)youdaoicibaDictYouDict[capital 词源字典]
early 13c., "of or pertaining to the head," from Old French capital, from Latin capitalis "of the head," hence "capital, chief, first," from caput (genitive capitis) "head" (see capitulum). Meaning "main, principal, chief, dominant, most important" is from early 15c. in English. Capital letter for an upper case one is attested from late 14c. The modern informal sense of "excellent, first-rate" is dated from 1762 in OED (as an exclamation of approval, OED's first example is 1875), perhaps from earlier use of the word in reference to ships, "first-rate, powerful enough to be in the line of battle," attested from 1650s, fallen into disuse after 1918.

A capital crime (1520s) is one that affects the life or "head;" capital had a sense of "deadly, mortal" from late 14c. in English, a sense also found in Latin. The felt connection between "head" and "life, mortality" also existed in Old English: as in heafodgilt "deadly sin, capital offense," heafdes þolian "to forfeit life." Capital punishment was in Blackstone (1765) and classical Latin capitis poena. Capital gain is recorded from 1921. Capital goods is recorded from 1899. Related: Capitally.[capital etymology, capital origin, 英语词源]