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

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common (adj.)
Origin and meaning of common

c. 1300, "belonging to all, owned or used jointly, general, of a public nature or character," from Old French comun "common, general, free, open, public" (9c., Modern French commun), from Latin communis "in common, public, shared by all or many; general, not specific; familiar, not pretentious." This is from a reconstructed PIE compound *ko-moin-i- "held in common," compound adjective formed from *ko- "together" + *moi-n-, suffixed form of root *mei- (1) "to change, go, move," hence literally "shared by all."

The second element of the compound also is the source of Latin munia "duties, public duties, functions," those related to munia "office." Perhaps reinforced in Old French by the Germanic form of PIE *ko-moin-i- (compare German gemein, Old English gemne "common, public, general, universal;" see mean (adj.)), which came to French via Frankish.

Used disparagingly of women and criminals since c. 1300. Meaning "pertaining equally to or proceeding equally from two or more" is from c. 1400. Meaning "usual, not exceptional, of frequent occurrence" is from late 14c. Sense of "not distinguished, belonging to the general mass" is from c. 1400; of things, "ordinary, not excellent," late 14c.

Common pleas is 13c., from Anglo-French communs plets, hearing civil actions by one subject against another as opposed to pleas of the crown. Common prayer is that done in public in unity with other worshipers; contrasted with private prayer. Common stock is attested from 1888. Common speech (late 14c.) is the vernacular, as opposed to Latin. Common good (late 14c.) translates Latin bonum publicum "the common weal." The college common room (1660s) is one to which all members have common access. 

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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."
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common (n.)
Origin and meaning of common

c. 1300, "a fellowship or brotherhood; early 14c., "people of a community or town, freemen, citizenry;" late 15c., "land held in common," from Old French commune and Medieval Latin communia, and partly from common (adj.). Also compare commons. Latin communis "common, general" (adj.) also served as a noun meaning "common property; state, commonwealth."

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common law (n.)

mid-14c., "the customary and unwritten laws of England as embodied in commentaries and old cases" (see common (adj.)), as opposed to statute law. Phrase common-law marriage is attested from 1909.

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common-sensical (adj.)

1839, from common sense, with ending as in nonsensical, etc. Common-sensible is attested from 1848.

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