"scurf, dandruff," 1786; earlier dandro (1590s), of uncertain origin (see dandruff).

"temper, anger, passion," 1831, American English, of unknown origin; perhaps a figurative use somehow of dander (n.1), or of West Indian dander, dunder "fermentation of sugar" (in English from 1796), from Spanish redundar "to overflow," from Latin redundare (see redundant).

"give the style or character of a dandy to," 1823, from dandy (n.) + -fy. Related: Dandified.

"to shake or move up and down in the arms or on the knee," 1520s, of unknown origin. Perhaps somehow felt to be imitative. Compare Italian dondolare "to dandle, swing," and French dandiner, from Old French dandin "small bell," imitative of its sound. Related: Dandled; dandling.

"scurf which forms on the scalp or skin of the head and comes off in small scales or dust," 1540s; the first element is obscure (despite much speculation, OED concludes "nothing satisfactory has been suggested"). The second element probably is Northumbrian or East Anglian dialectal huff, hurf "scab," from Old Norse hrufa, from Proto-Germanic *hreufaz, source of Old English hreofla "leper." Middle English words for it were bran (late 14c.), furfur (c. 1400, from Latin), scales (mid-15c.).

"man who draws attention by unusual finery of dress and fastidiousness manners, a fop," c. 1780, of uncertain origin; attested earliest in a Scottish border ballad:

I've heard my granny crack

O' sixty twa years back

When there were sic a stock of Dandies O

etc. In that region, Dandy is diminutive of Andrew (as it was in Middle English generally). OED notes that the word was in vogue in London c. 1813-1819. His female counterpart was a dandizette (1821) with French-type ending.

Meaning "anything superlative or fine" is from 1786. As an adjective, "characteristic of a dandy, affectedly neat and trim," by 1813; earlier in the sense of "fine, splendid, first-rate" (1792) and in this sense it was very popular c. 1880-1900.

The popular guess, since at least 1827, is that it is from French Dandin, a mock surname for a foolish person used in 16c. by Rabelais (Perrin Dandin), also by Racine, La Fontaine, and Molière, from dandiner "to walk awkwardly, waddle." Farmer rejects this and derives it from dandyprat, an Elizabethan word for "a dwarf; a page; a young or insignificant person," originally (early 16c.) the name of a small silver coin. Both words are of unknown origin, and OED finds the connection of both to dandy to be "without any apparent ground." English dandy was itself borrowed into French c. 1830.

Jack-a-Dandy, or Jack O'Dandy figures in writings from the early 17c. He is listed among other famous Jacks in "Iack a Lent" (1620) and is sometimes defined as an impertinent little man, but other uses are unclear as to sense and in at least one instance from 1620s he is a bogeyman character.

DANDY was first applied half in admiration half in derision to a fop about the year 1816. John Bee (Slang Dict., 1823) says that Lord Petersham was the chief of these successors to the departed Macaronis, and gives, as their peculiarities, 'French gait, lispings, wrinkled foreheads, killing king's English, wearing immense plaited pantaloons, coat cut away, small waistcoat, cravat and chitterlings immense, hat small, hair frizzled and protruding.' [Farmer and Henley, "Slang and its Analogues," 1891]

"native or inhabitant of Denmark," early 14c. (in plural, Danes), from Danish Daner, (Medieval Latin Dani), which is perhaps ultimately from a source related to Old High German tanar "sand bank," in reference to their homeland, or from Proto-Germanic *den- "low ground," for the same reason.

It replaced Old English Dene (plural), which was used of Northmen generally. Shakespeare has Dansker "a Dane" (c. 1600). Dane was applied by 1774 to a breed of large dogs.

Danegeld (attested from 1086; it was first imposed in 991) supposedly originally was a tax to pay for protection from the Northmen (either to outfit defensive armies or to buy peace), continued under later kings for other purposes. Danelaw (c. 1050) was "the body of Danish law in force over that large part of England under Viking rule after Alfred's treaty in 878;" the application to the land itself is modern (1837, Danelagh).

1781 (in Sophia Lee's comedy "A Chapter of Accidents," which was acted first in 1780), a minced euphemism for damn.

mid-13c., daunger, "arrogance, insolence;" c. 1300, "power of a lord or master, jurisdiction," from Anglo-French daunger, Old French dangier "power, power to harm, mastery, authority, control" (12c., Modern French danger), alteration (due to association with damnum) of dongier, from Vulgar Latin *dominarium "power of a lord," from Latin dominus "lord, master," from domus "house" (from PIE root *dem- "house, household").

Modern sense of "risk, peril, exposure to injury, loss, pain, etc." (from being in the control of someone or something else) evolved first in French and was in English by late 14c. For this, Old English had pleoh; in early Middle English this sense is found in peril. For sound changes, compare dungeon, which is from the same source.

c. 1200, daungerous, "difficult to deal with, arrogant, severe" (the opposite of affable), from Anglo-French dangerous, Old French dangeros (12c., Modern French dangereux), from danger "power, power to harm, mastery, authority, control" (see danger).

In Chaucer, it can mean "hard to please; reluctant to give; overbearing." The modern sense of "involving danger, hazardous, unsafe, risky, liable to inflict injury or harm" is from c. 1400. Other words formerly used in this sense included dangersome (1560s), dangerful (1540s). Related: Dangerously.