- down[down 词源字典]
- down: Effectively, English now has three distinct words down, but two of them are intimately related: for down ‘to or at a lower place’  originally meant ‘from the hill’ – and the Old English word for hill in this instance was dūn. This may have been borrowed from an unrecorded Celtic word which some have viewed as the ultimate source also of dune  (borrowed by English from Middle Dutch dūne) and even of town.
Its usage is now largely restricted to the plural form, used as a geographical term for various ranges of hills (the application to the North and South Downs in southern England dates from at least the 15th century). The Old English phrase of dūne ‘from the hill’ had by the 10th century become merged into a single word, adūne, and broadened out semantically to ‘to a lower place, down’, and in the 11th century it started to lose its first syllable – hence down.
Its use as a preposition dates from the 16th century. (The history of down is closely paralleled in that of French à val, literally ‘to the valley’, which also came to be used for ‘down’; it is the source of French avaler ‘descend, swallow’, which played a part in the development of avalanche.) Down ‘feathers’  was borrowed from Old Norse dúnn.
=> dune[down etymology, down origin, 英语词源]
- down (adv.)
- late Old English shortened form of Old English ofdune "downwards," from dune "from the hill," dative of dun "hill" (see down (n.2)). A sense development peculiar to English.
Used as a preposition since c. 1500. Sense of "depressed mentally" is attested from c. 1600. Slang sense of "aware, wide awake" is attested from 1812. Computer crash sense is from 1965. As a preposition from late 14c.; as an adjective from 1560s. Down-and-out is from 1889, American English, from situation of a beaten prizefighter. Down home (adj.) is 1931, American English; down the hatch as a toast is from 1931; down to the wire is 1901, from horse-racing. Down time is from 1952. Down under "Australia and New Zealand" attested from 1886; Down East "Maine" is from 1825; Down South "in the Southern states of the U.S." is attested by 1834.
- down (n.1)
- "soft feathers," late 14c., from Old Norse dunn, perhaps ultimately from PIE root *dheu- (1) "to fly about (like dust), to rise in a cloud."
- down (n.2)
- Old English dun "down, moor; height, hill, mountain," from Proto-Germanic *dunaz- (cognates: Middle Dutch dunen "sandy hill," Dutch duin), "probably a pre-insular loan-word from Celtic" [Cambridge Dictionary of English Place-Names], in other words, borrowed at a very early period, before the Anglo-Saxon migration, from PIE root *dheue- "to close, finish, come full circle." Meaning "elevated rolling grassland" is from c. 1300.
The non-English Germanic words tend to mean "dune, sand bank" (see dune), while the Celtic cognates tend to mean "hill, citadel" (compare Old Irish dun "hill, hill fort;" Welsh din "fortress, hill fort;" and second element in place names London, Verdun, etc.). German Düne, French dune, Italian, Spanish duna are said to be loan-words from Dutch.
- down (v.)
- 1560s, from down (adv.). Meaning "swallow hastily" is by 1860; football sense of "bring down (an opposing player) by tackling" is attested by 1887. Related: Downed; downing.