"edged or pointed weapon for thrusting, shorter than a sword," late 14c. (mid-14c. in Anglo-Latin), apparently related to Old French dague "dagger," from Old Provençal or Italian daga, which are of uncertain origin; perhaps from Celtic, perhaps from Vulgar Latin *daca "Dacian knife," from the Roman province (see Dacian). The ending is possibly the faintly pejorative -ard suffix.

Attested earlier (1279) as a surname (Dagard, presumably "one who carried a dagger"). Also compare dogwood. Middle Dutch dagge, Danish daggert, German Degen also are from French. By 16c.-17c. swordsmen held it in the left hand to parry thrusts from the opponent's rapier. As "a reference mark in the form of a dagger," by 1706.

1823, from Spanish Diego "James" (see James). Said to have been originally American English slang for "one born of Spanish parents," especially in New Orleans; it was also used of Spanish or Portuguese sailors on English or American ships. By 1900 it had broadened to include non-sailors and shifted to mean chiefly "Italian." James the Greater is the patron saint of Spain, and Diego as generic for "a Spaniard" is attested in English from 1610s. Dago red "cheap Italian wine" is attested by 1899.

god of the Philistines, represented as having the upper body of a man and the lower part of a fish, late 14c. (Judges xvi.23), from Hebrew Dagon, from dag "fish."

"picture taken with an early photographic process involving silver plates, iodine, and vapor of mercury," 1839, from French daguerreotype, coined from the name of the inventor, Louis J.M. Daguerre (1789-1851) + -type (see type (n.)). As a verb from 1839. Related: Daguerreotypist.

type of cast-iron smooth-bore naval artillery cannon, by 1854, named for its inventor, U.S. naval ordnance officer John A. Dahlgren (1809-1870), who was of Swedish ancestry.

genus of plants native to Mexico and Central America, 1804, named 1791 by Spanish botanist Antonio José Cavanilles for Anders Dahl (1751-1789), Swedish botanist and pupil of Linnaeus, who discovered it for science in Mexico in 1788.

The likelihood that a true blue variety of the flower never could be cultivated was first proposed by French-Swiss botanist Augustin Pyramus de Candolle, and noted in English by 1835; hence blue dahlia, figurative expression for "something impossible or unattainable" (1843).

18c.-19c. West African kingdom, a native name of unknown etymology. Made a French protectorate in 1894, it gained full independence in 1960, and in 1975 changed its name to Benin. Related: Dahoman, Dahomean.

c. 1300, "platform or raised floor at one end of a room or hall," from Anglo-French deis, Old French dais, dois "platform, high table," from Latin discus "disk-shaped object," also, in Medieval Latin, "table," from Greek diskos "quoit, disk, dish" (see disk (n.)). It died out in English c. 1600, was preserved in Scotland, and was revived 19c. by antiquarians.

Old English dæg "period during which the sun is above the horizon," also "lifetime, definite time of existence," from Proto-Germanic *dages- "day" (source also of Old Saxon, Middle Dutch, Dutch dag, Old Frisian di, dei, Old High German tag, German Tag, Old Norse dagr, Gothic dags), according to Watkins, from PIE root *agh- "a day." He adds that the Germanic initial d- is "of obscure origin." But Boutkan says it is from PIE root *dhegh- "to burn" (see fever). Not considered to be related to Latin dies (which is from PIE root *dyeu- "to shine").

Meaning originally, in English, "the daylight hours;" it expanded to mean "the 24-hour period" in late Anglo-Saxon times. The day formerly began at sunset, hence Old English Wodnesniht was what we would call "Tuesday night." Names of the weekdays were not regularly capitalized in English until 17c.

From late 12c. as "a time period as distinguished from other time periods." From day to day was in late Old English; day-by-day "daily" is from late 14c.; all day "all the time" is from late 14c. Day off "day away from work" is attested from 1883; day-tripper first recorded 1897. The days in nowadays, etc. is a relic of the Old English and Middle English use of the adverbial genitive.

All in a day's work "something unusual taken as routine" is by 1820. The nostalgic those were the days is attested by 1907. That'll be the day, expressing mild doubt following some boast or claim, is by 1941. To call it a day "stop working" is by 1919; earlier call it a half-day (1838). One of these days "at some day in the near future" is from late 15c. One of those days "a day of misfortune" is by 1936.

"happening or being every day," mid-15c.; see day + -ly (1). Compare Old English dglic, a form found in compounds: twadglic "happening once in two days," reodglic "happening once in three days." The more usual Old English adjective was dghwamlic (also dgehwelc), which became Middle English daiwhamlich. Cognate with German tglich.

As an adverb, "every day, day by day," early 15c. (the Old English adverb was dghwamlice. As a noun, "a daily newspaper," by 1832.