late 14c., "one who lives under the patronage of another," from Anglo-French clyent (c. 1300), from Latin clientem (nominative cliens) "follower, retainer" (related to clinare "to incline, bend"), from PIE *klient-, a suffixed (active participle) form of root *klei- "to lean." The notion apparently is "one who leans on another for protection." In ancient Rome, a plebeian under the guardianship and protection of a patrician (who was called patronus in this relationship; see patron).
The meaning "a lawyer's customer" is attested from c. 1400, and by c. 1600 the word was extended to any customer who puts a particular interest in the care and management of another. Related: Cliency.
The relation of client and patron between a plebeian and a patrician, although at first strictly voluntary, was hereditary, the former bearing the family name of the latter, and performing various services for him and his family both in peace and war, in return for advice and support in respect to private rights and interests. Foreigners in Rome, and even allied or subject states and cities, were often clients of Roman patricians selected by them as patrons. The number of a patrician's clients, as of a baron's vassals in the middle ages, was a gage his greatness. [Century Dictionary]
1560s, "body of professed adherents, clients collectively under the patronage of someone," from French clientèle (16c.), from Latin clientela "relationship between dependent and patron; body of clients," from clientem (nominative cliens, "follower, retainer;" see client).
The word is said in OED to apparently have become obsolete after 17c., and the main modern meaning "customers, those who regularly patronize a business or professional" is from 1857, perhaps a reborrowing from French (it was used in English in italics as a foreign word from 1836).
Clientage is attested from 1630s as "a body of clients;" clientship from 1640s as "condition of being a client."
Proto-Indo-European root meaning "to lean."
It forms all or part of: acclivity; anticline; clemency; client; climate; climax; cline; clinic; clinical; clino-; clitellum; clitoris; decline; declivity; enclitic; heteroclite; incline; ladder; lean (v.); lid; low (n.2) "small hill, eminence;" matroclinous; patroclinous; polyclinic; proclitic; proclivity; recline; synclinal; thermocline.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit srayati "leans," sritah "leaning;" Old Persian cay "to lean;" Lithuanian šlyti "to slope," šlieti "to lean;" Latin clinare "to lean, bend," clivus "declivity," inclinare "cause to bend," declinare "bend down, turn aside;" Greek klinein "to cause to slope, slant, incline;" Old Irish cloin "crooked, wrong;" Middle Irish cle, Welsh cledd "left," literally "slanting").
also necessaries, mid-14c., "that which is indispensable; needed, required, or useful things; the necessities of life; actions determined by right or law; that which cannot be disregarded or omitted," perhaps from Old French necessaire (n.) "private parts, genitalia; lavatory," and directly from Latin necessarius (n.), in classical Latin "a relation, relative, kinsman; friend, client, patron;" see necessary (adj.).
also non-chalant, "indifferent, unconcerned, careless, cool," 1734, from French nonchalant "careless, indifferent," present participle of nonchaloir "be indifferent to, have no concern for" (13c.), from non- "not" (see non-) + chaloir "have concern for," ultimately from Latin calere "be hot" (from PIE root *kele- (1) "warm"). French chaland "customer, client" is of the same origin. Related: Nonchalantly.
1570s, in military sense, "an armed guard," later generally, "a protecting, guiding, or honorary guard; protection or safeguard on a journey or excursion," from French escorte (16c.), from Italian scorta, literally "a guiding," from scorgere "to guide," from Vulgar Latin *excorrigere, from ex- "out" (see ex-) + Latin corrigere "set right" (see correct (v.)). The sense of "person accompanying another to a social occasion" is 1936; as a person hired by a client for sexual services by 1974.
late 14c. lauier, lawer, lawere (mid-14c. as a surname), "one versed in law, one whose profession is suits in court or client advice on legal rights," from Middle English lawe "law" (see law) + -iere. Spelling with -y- predominated from 17c. (see -yer). In the New Testament (Luke xiv.3, etc.) "interpreter of Mosaic law." Old English had lahwita, with wita "sage, wise man; adviser councilor," and an earlier Middle English word for "lawyer" was man-of-law (mid-14c.). Related: Lawyerly.
early 15c., "the bringing of something to bear on something else," from Old French aplicacion (14c.), from Latin applicationem (nominative applicatio) "a joining to, an attaching oneself to; relation of a client to a patron," noun of action from past-participle stem of applicare "attach to, join, connect," from ad "to" (see ad-) + plicare "to fold" (from PIE root *plek- "to plait").
Meaning "sincere hard effort" is from c. 1600. Meaning "a formal request to be hired for a job or paid position" is by 1851. Computer sense "program designed to carry out specific tasks or solve specific problems within a larger system" is a shortening of application program (1969).
early 15c., "a cheat, a mean ruse," from Old North French trique "trick, deceit, treachery, cheating," from trikier "to deceive, to cheat," variant of Old French trichier "to cheat, trick, deceive," of uncertain origin, probably from Vulgar Latin *triccare, from Latin tricari "be evasive, shuffle," from tricæ "trifles, nonsense, a tangle of difficulties," of unknown origin.
Meaning "a roguish prank" is recorded from 1580s; sense of "the art of doing something" is first attested 1610s. Meaning "prostitute's client" is first attested 1915; earlier it was U.S. slang for "a robbery" (1865).
To do the trick "accomplish one's purpose" is from 1812; to miss a trick "fail to take advantage of opportunity" is from 1889; from 1872 in reference to playing the card-game of whist, which might be the original literal sense. Trick-or-treat as a children's Halloween pastime is recorded from 1927 in Canada. Trick question is from 1907.
Old English læppa (plural læppan) "skirt or flap of a garment," from Proto-Germanic *lapp- (source also of Old Frisian lappa, Old Saxon lappo, Middle Dutch lappe, Dutch lap, Old High German lappa, German Lappen "rag, shred," Old Norse leppr "patch, rag"), of uncertain origin.
Sense of "lower front part of a shirt or skirt" led to that of "upper legs of seated person" (c. 1300). Used figuratively ("bosom, breast, place where someone or something is held and cherished") from late 14c., as in lap of luxury (which is first recorded 1802). To drop or dump something in someone's lap "shift a burden" is from 1962. From 15c.-17c. the word (often in plural) was a euphemism for "female pudendum," but this is not the source of lap dance, which is first recorded 1993.
To lap dance, you undress, sit your client down, order him to stay still and fully clothed, then hover over him, making a motion that you have perfected by watching Mister Softee ice cream dispensers. [Anthony Lane, review of "Showgirls," New Yorker, Oct. 16, 1995]
Lap-clap was old slang for "an act of coition" (c. 1600), in warning expressions to youth often paired with lip-clip "a kiss." Also compare slang Lapland "the society of women."