英语词源字典 - 在线词源网站

equal [equal 词源字典]: equal: [14] Latin aequus (a word of unknown ancestry) meant ‘level’ or ‘even’. From it was derived the adjective aequālis ‘equal’, which has provided the term for ‘equal’ in all the modern Romance languages, including French égal (source of English egalitarian [19]), Italian uguale, and Spanish igual. English, however, is the only Germanic language in which it constitutes a major borrowing.

English also possesses, of course, a host of related words, including adequate [17], equanimity [17], equate [15], equation [14] equator [14] (etymologically the line of latitude that ‘equalizes’ day and night), and iniquity [14] (etymologically the equivalent of inequality), not to mention all those beginning with the prefix equi-, such as equidistant [16], equilibrium [17] (literally ‘equal balance’, from Latin lībra ‘balance’), equinox [14], equity [14], and equivalent [15].
=> adequate, egalitarian, equator, equity, iniquity[equal etymology, equal origin, 英语词源]
twilight: twilight: [15] Twilight is etymologically ‘light between day and night’. The word was compounded from the prefix twi- ‘two’, apparently used here in the sense ‘between’ (between itself comes from the same ultimate source as two) and light. German has the parallel zwielicht.
=> two
equator (n.): late 14c., from Medieval Latin aequator (diei et noctis) "equalizer (of day and night)," agent noun from Latin aequare "make equal" (see equate). When the sun is on the celestial equator, twice annually, day and night are of equal length. Sense of "celestial equator" is earliest, extension to "terrestrial line midway between the poles" first recorded in English 1610s.
equinox (n.): c. 1400, "point at which the sun crosses the earth's equator, making day and night of equal length everywhere," from Old French equinoce (12c.) or directly from Medieval Latin equinoxium "equality of night (and day)," from Latin aequinoctium, usually in plural, dies aequinoctii "the equinoxes," from aequus "equal" (see equal (adj.)) + nox (genitive noctis) "night" (see night). The Old English translation was efnniht. Related: Equinoctial.
swing-shift (n.): 1941 (typically 4 p.m. to midnight), from the notion of "facing both ways" between day and night shifts; see swing (v.) + shift (n.).
equinoctial: "Happening at or near the time of an equinox", Late Middle English (in the sense 'relating to equal periods of day and night'): via Old French from Latin aequinoctialis, from aequinoctium (see equinox).