"a trench made by digging," especially a trench for draining wet land," Middle English diche, from Old English dic "ditch, dike," a variant of dike (q.v.), which at first meant "an excavation," but later in Middle English was applied to the ridge or bank of earth thrown up in excavating. Middle English diche also could mean "a defensive wall."
As the earth dug out of the ground in making a trench is heaped up on the side, the ditch and the bank are constructed by the same act, and it is not surprising that the two should have been confounded under a common name. [Hensleigh Wedgwood, "A Dictionary of English Etymology," 1859]
Ditch-water "stale or stagnant water that collects in ditches" is from mid-14c. In Middle English, digne as dich water (late 14c.) meant "foolishly proud." Also see last-ditch.
late 14c., "surround with a ditch; dig a ditch or ditches in;" from ditch (n.). Meaning "to throw into a ditch" is from 1816, later especially "to throw a train off the tracks," hence the slang sense of "abandon, discard (as if throwing into a ditch)," first recorded 1899 in American English, and in reference to aircraft "to bring down into the sea," by 1941. The last might have been from or reinforced by the use of the ditch in naval slang for "the sea" (1922). Related: Ditched; ditching.
"on the last line of defense," 1909, from an image attested by 1715, from a quote attributed to William of Orange (1650-1702), who is said to have uttered it defiantly during the French invasion of 1672; if so, originally in a Netherlands context.
We have no space to enter into the detail of the heroic struggle maintained by the young stadtholder and his faithful Dutchmen; how they laid their country under water, and successfully kept the powerful invader at bay. Once the contest seemed utterly hopeless. William was advised to compromise the matter, and yield up Holland as the conquest of Louis XIV. "No," replied he; "I mean to die in the last ditch." A speech alone sufficient to render his memory immortal. [Agnes Strickland, "Lives of the Queens of England," London, 1847]
c. 1300, mote "a mound, a hill" (a sense now obsolete); late 14c., "ditch or deep trench dug round the rampart of a castle or other fortified place," from Old French mote "mound, hillock, embankment; castle built on a hill" (12c.; Modern French motte) and directly from Medieval Latin mota "mound, fortified height," a word of unknown origin, perhaps from Gaulish mutt, mutta.
The sense shifted in Norman French from the castle mound to the ditch dug around it. For a similar evolution, compare ditch (n.) and dike. As a verb, "to surround with a moat," early 15c. Related: Moated.
Old English dic "trench, ditch; an earthwork with a trench; moat, channel for water made by digging," from Proto-Germanic *dikaz (source also of Old Norse diki "ditch, fishpond," Old Frisian dik "dike, mound, dam," Middle Dutch dijc "mound, dam, pool," Dutch dijk "dam," German Deich "embankment"), from PIE root *dheigw- "to pierce; to fix, fasten." The sense evolution would be "to stick (a spade, etc.) in" the ground, thus, "to dig," thus "a hole or other product of digging."
This is the northern variant of the word that in the south of England yielded ditch (n.). At first "an excavation," later applied to the ridge or bank of earth thrown up in excavating a ditch or canal (late 15c.), a sense development paralleled by the cognate words in many languages, though naturally it occurred earlier in Dutch and Frisian. From 1630s specifically as "ridge or bank of earth to prevent lowlands from being flooded." In geology, "vertical fissure in rocks filled with later material which made its way in while molten" (1835).
c. 1200, diggen, "to make a ditch or other excavation," a word of uncertain origin, perhaps related to dike and ditch, either via Anglo-French diguer, from Old French digue "dike" (which is ultimately from Proto-Germanic *dīk-, from PIE root *dheigw- "to stick, fix") or directly from an unrecorded Old English verb. The older native words were deolfan (see delve), grafan (see grave (v.)).
Transitive meanings "form by excavation, make by digging," also "obtain or remove by excavation" are from late 14c.; figurative sense of "discover by effort or search" is from early 15c. Meaning "to penetrate" is from mid-15c.; transitive sense of "cause to penetrate, thrust or force in" is by 1885.
In 19c. U.S. student slang it meant "study hard, give much time to study" (1827); the 20c. slang sense of "understand" is recorded by 1934 in African-American vernacular. Both probably are based on the notion of "excavate." A slightly varied sense of "appreciate" emerged by 1939. The strong past participle dug appeared in 16c. but is not etymological.
"to make a ditch," Old English dician "make a ditch, surround with a ditch or dike, enclose with a dike or ditches," from the source of dike (n.). Related: Diked; diking.