英语词源字典 - 在线词源网站

meridian [meridian 词源字典]: meridian: [14] Etymologically, meridian denotes the ‘middle of the day’. It comes via Old French from Latin merīdiānus, a derivative of merīdiēs ‘mid-day’. This was an alteration of an earlier medidiēs, a compound noun formed from medius ‘middle’ (source of English medium) and diēs ‘day’. The application of the word to a circle passing round the Earth or the celestial sphere, which is an ancient one, comes from the notion of the sun crossing it at noon.
=> medium[meridian etymology, meridian origin, 英语词源]
zodiac: zodiac: [14] The zodiac is etymologically a circle of ‘little animals’. Greek zóidion originally denoted a ‘carved figure of an animal’ (it was a diminutive of zóion ‘animal’, a relative of English zoo). From it was derived the adjective zōidiakós, which was used in the expression zōidiakós kúklos ‘circle of carved figures’, denoting the twelve figures or signs representing the divisions of a band around the celestial sphere. Zōidiakós became a noun in its own right, and passed into English via Latin zōdiacus and French zodiaque.
=> zoo
hemisphere (n.): late 14c., hemysperie, in reference to the celestial sphere, from Latin hemisphaerium, from Greek hemisphairion, from hemi- "half" (see hemi-) + sphaira "sphere" (see sphere). Spelling reformed 16c. Of the Earth, from 1550s; of the brain, 1804.
sphere (n.): mid-15c., Latinized spelling of Middle English spere (c. 1300) "cosmos; space, conceived as a hollow globe about the world," from Anglo-French espiere, Old French espere (13c., Modern French sphère), from Latin sphaera "globe, ball, celestial sphere" (Medieval Latin spera), from Greek sphaira "globe, ball, playing ball, terrestrial globe," of unknown origin.

From late 14c. in reference to any of the supposed concentric, transparent, hollow, crystalline globes of the cosmos believed to revolve around the earth and contain the planets and the fixed stars; the supposed harmonious sound they made rubbing against one another was the music of the spheres (late 14c.). Also from late 14c. as "a globe; object of spherical form, a ball," and the geometric sense "solid figure with all points equidistant from the center." Meaning "range of something, place or scene of activity" is first recorded c. 1600 (as in sphere of influence, 1885, originally in reference to Anglo-German colonial rivalry in Africa).
tropic (n.): late 14c., "either of the two circles in the celestial sphere which describe the northernmost and southernmost points of the ecliptic," from Late Latin tropicus "of or pertaining to the solstice" (as a noun, "one of the tropics"), from Latin tropicus "pertaining to a turn," from Greek tropikos "of or pertaining to a turn or change; of or pertaining to the solstice" (as a noun, "the solstice," short for tropikos kyklos), from trope "a turning" (see trope).

The notion is of the point at which the sun "turns back" after reaching its northernmost or southernmost point in the sky. Extended 1520s to the corresponding latitudes on the earth's surface (23 degrees 28 minutes north and south); meaning "region between the tropics of Cancer and Capricorn" is from 1837.