early 15c., dependaunce, "consequence, result, relation of a conclusion to a premise or an effect to a cause," from Old French dépendance (from dependre; see depend) and from Medieval Latin dependentia. Originally also dependance (which is the older of the two modern spellings), depending whether the writer had French or Latin foremost in mind; the Latin form gradually predominated, and after c. 1800 the spelling dependance is rare. For discussion, see dependant (n.).
From mid-15c. as "state of deriving existence, support, or direction from another." From 1620s as "reliance, confidence, trust." Literal meaning "fact of hanging from something" (1690s) was rare and is obsolete.
early 15c., originally in law, "action growing out of another action," from the adjective (see dependent) or from noun use of the adjective in French. It is attested from 1580s as "one who depends on or looks to another for support or favor."
As with its relative, dependence, it co-existed with the Latin-influenced variant (in this case dependent, from Latin dependere) through 18c., but with this word the French spelling (dpendant for both adjective and noun) has proven more durable in English, possibly because it has been found convenient to keep both, one (dependant) for the noun, the other (dependent) for the adjective.
But Century Dictionary (1897) places all senses under dependent, and writes:
As the spelling of this class of words depends solely upon whether they happen to be regarded as derived directly from the French or directly from the Latin, and as usage is divided, there is no good reason for insisting upon a distinction in spelling between the noun and the adjective ....
1845, in reference to the doctrine of French anarchist/socialist Pierre-Joseph Proudhon (1809-1865) that individual and collective well-being is attainable only by mutual dependence, from French mutuellisme. In biology, "a symbiosis in which two organisms living together mutually and permanently help and support one another," from 1876, from mutual + -ism.
1580s, "suitable connection or dependence, consistency" (in narrative or argument), also more literally "act or state of sticking or cleaving of one thing to another," from French cohérence (16c.), from Latin cohaerentia, abstract noun from cohaerentem(nominative cohaerens), present participle of cohaerere "to stick together, be coherent," from assimilated form of com "together" (see co-) + haerere "to adhere, stick" (see hesitation). Related: Coherency.
1834, "fact or condition of being relative, existence as an immediate object of the understanding or experience, existence only in relation to a thinking mind," (apparently coined by Coleridge, in "Notes on Waterland's Vindication of Christ's Divinity"), from relative (adj.) + -ity. In scientific use, connected to the theory of Albert Einstein (1879-1955) having to do with the dependence of observation on the relative motion of observer and object, published in 1905 (special theory of relativity) and 1915 (general theory of relativity), but the word was used in roughly this sense by J.C. Maxwell in 1876. An earlier noun in the sense of "state of being relative" was relativeness (1670s).
1816, in the figurative sense of "icy reception, studied neglect or indifference," first in Sir Walter Scott, probably originally a literal figure (see cold (adj.)), but commonly used with a punning reference to "cold shoulder of mutton," considered a poor man's dish and thus, perhaps, something one would set out for an unwanted guest with deliberate intention to convey displeasure.
How often have we admired the poor knight, who, to avoid the snares of bribery and dependence, was found making a second dinner from a cold shoulder of mutton, above the most affluent courtier, who had sold himself to others for a splendid pension! ["No Fiction," 1820]
Originally with to show, later to give. As a verb from 1845; related: cold-shouldered. Also compare cold roast, old slang for "something insignificant." Cold pig was a 19c. term for throwing cold water on a sleeping person to wake him or her.