Etymology
Advertisement
ground (n.)

Old English grund "bottom; foundation; surface of the earth," also "abyss, Hell," and "bottom of the sea" (a sense preserved in run aground), from Proto-Germanic *grundu-, which seems to have meant "deep place" (source also of Old Frisian, Old Saxon, Danish, Swedish grund, Dutch grond, Old High German grunt, German Grund "ground, soil, bottom;" Old Norse grunn "a shallow place," grund "field, plain," grunnr "bottom"). No known cognates outside Germanic.

Sense of "reason, motive" first attested c. 1200. Meaning "source, origin, cause" is from c. 1400. Electrical sense "connection with the earth" is from 1870 (in telegraphy). Meaning "place where one takes position" is from 1610s; hence stand (one's) ground (1707). To run to ground in fox-hunting is from 1779. Ground rule (1890) originally was a rule designed for a specific playing field (ground or grounds in this sense attested by 1718); by 1953 it had come to mean "a basic rule."

Related entries & more 
Advertisement
ground (adj.)

"reduced to fine particles by grinding," 1765, past-participle adjective from grind (v.).

Related entries & more 
gain (n.)

c. 1200, gein, "advantage, benefit; help," c. 1300, "reward, profit, that which has been acquired" (possessions, resources, wealth), from Old French gain, gaaigne "gain, profit, advantage; work, business; booty; arable land" (12c.), from Germanic, and from Old Norse (see gain (v.)). Meaning "any incremental increase" (in weight, etc.) is by 1851. Related: Gains. The French word enfolded the notions of "profit from agriculture" and "booty, prey."

Related entries & more 
gain (v.)

1520s, "obtain as profit," from French gagner, from Old French gaaignier "to earn, gain; trade; capture, win," also "work in the fields, cultivate land," from Frankish *waidanjan "hunt, forage," also "graze, pasture," from Proto-Germanic *waithanjan "to hunt, plunder," from *waithjo- "pursuit, hunting" (source also of Old English waþ "hunting," German Weide "pasture, pasturage," Old Norse veiðr "hunting, fishing, catch of fish").

This is from PIE root *weie- "to go after, strive after, pursue vigorously, desire," with noun derivatives indicating "force, power" (related to *wi-ro- "man;" see virile). Cognates include Sanskrit padavi- "track, path, trail," veti- "follows, strives, leads, drives;" Avestan vateiti "follows, hunts;" Greek hiemai "move oneself forward, strive, desire;" Lithuanian vyti "to chase, pursue;" Old Norse veiðr "chase, hunting, fishing;" Old English OE wað "a chase, hunt."

Meaning "obtain by effort or striving" is from 1540s; intransitive sense of "profit, make gain" is from 1570s. Meaning "arrive at" is from c. 1600. Of timepieces by 1861. Related: Gained; gaining. To gain on "advance nearer" is from 1719. To gain ground (1620s) was originally military.

Related entries & more 
ground (v.)

mid-13c., "to put on the ground, to strike down to the ground;" late 14c., "lay the foundation of," also, figuratively, "to base" (an argument, sermon, etc.), from ground (n.). Meaning "instruct thoroughly in the basics" is from late 14c. Of ships, "to run into the ground," from mid-15c. (intransitive), transitive sense from 1650s. Of arms, from 1711. Electrical sense from 1881. Meaning "deny privileges" is 1940s, originally a punishment meted out to pilots (in which sense it is attested from 1930). In the sense "establish firmly" Old English had grundweallian, grundstaðelian; also gryndan "descend," gegryndan "to found."

Related entries & more 
Advertisement
ground-swell (n.)

also groundswell, "broad, deep swell of the sea," 1783, from ground (n.) + swell (n.). Figurative sense (of sound, emotion, etc.) is attested from 1817.

Related entries & more 
ground-breaking (adj.)

also groundbreaking, 1907 as a figurative adjective, from expression to break ground (1650s), either for planting or for building, which was in figurative use by 1884; see ground (n.) + break (v.).

Related entries & more 
camp-ground (n.)

also campground, "place for camping," 1806, from camp (n.) or (v.) + ground (n.).

Related entries & more 
ground-hog (n.)

also groundhog, "American marmot," 1784, from ground (n.) + hog (n.). Also known colloquially as a whistlepig, woodchuck, and compare aardvark. Ground Hog Day as a weather forecasting event is first recorded 1869, in an Ohio newspaper article that calls it "old tradition;" the custom though not the name, attested from 1850s. Similar superstitions are widespread; Webster ("The White Devil") refers to one from Elizabethan London:

Let all that belong to great men remember th' old wives'
tradition, to be like the lions i'th' Tower on Candlemasday ;
to mourn if the sun shine, for fear of the pitiful remainder
of winter to come.
Related entries & more 
ground zero (n.)

1946, originally with reference to atomic blasts. In reference to the Sept. 11, 2001, terrorist attack on New York, it was in use by Sept. 13.

Related entries & more