Etymology
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commercial (adj.)

1680s, "engaging in trade," from commerce + -al (1). Meaning "done for the sake of financial profit" (of art, etc.), "prepared for the market or as an article of trade" is from 1871. Meaning "paid for by advertisements" (in reference to radio, TV, etc.) is from 1932. Related: Commercially.

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commercial (n.)

"an advertisement broadcast on radio or TV," 1935, from commercial (adj.). Earlier as a noun it was short for commercial traveler (1855).

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credit (n.)

1540s, "belief, faith," from French crédit (15c.) "belief, trust," from Italian credito, from Latin creditum "a loan, thing entrusted to another," neuter past participle of credere "to trust, entrust, believe" (see credo).

The commercial sense of "confidence in the ability and intention of a purchaser or borrower to make payment at some future time" was in English by 1570s (creditor is mid-15c.); hence "sum placed at a person's disposal" by a bank, etc., 1660s. From 1580s as "one who or that which brings honor or reputation to." Meaning "honor, acknowledgment of merit," is from c. 1600.

Academic sense of "point awarded for completing a course of study" is by 1904 (short for hour of credit (1892), given for satisfactory completion of one lecture, etc., a week, usually one hour in length). Movie/broadcasting sense "acknowledgement and naming of the individual contributors" (in plural, credits) is by 1914.

Credit rating is from 1958; credit union "cooperative banking society" is 1881, American English.

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company (n.)

mid-12c., "large group of people," from Old French compagnie "society, friendship, intimacy; body of soldiers" (12c.), from Late Latin companio, literally "bread fellow, messmate," from Latin com "with, together" (see com-) + panis "bread," from PIE root *pa- "to feed." Abbreviation co. dates from 1670s. 

Meaning "companionship, consort of persons one with another, intimate association" is from late 13c. Meaning "person or persons associated with another in any way" is from c. 1300. In Middle English the word also could mean "sexual union, intercourse" (c. 1300).

From late 14c. as "a number of persons united to perform or carry out anything jointly," which developed a commercial sense of "business association" by 1550s, the word having been used in reference to trade guilds from late 14c. Meaning "subdivision of an infantry regiment" (in 19c. usually 60 to 100 men, commanded by a captain) is from c. 1400. 

Meaning "person or persons with whom one voluntarily associates" is from c. 1600; phrase keep company "consort" is from 1560s (bear company in the same sense is from c. 1300). Expression two's company "two persons are just right" (for conversation, etc.), is attested from 1849; the following line varies: but three is none (or not), 1849; three's trumpery (1864); three's a crowd (1856). 

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credit (v.)

1540s, "to believe, be sure of the truth of," from credit (n.). In a looser sense, "to attribute, give as the cause of," 1850. Meaning "to enter upon the credit side of an account" is from 1680s. Related: Credited; crediting.

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credit-card (n.)

1952 in the modern sense; see credit (n.) + card (n.1). The phrase was used late 19c. to mean "traveler's check."

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photostat (n.)

1909, a type of copying machine (trademark Commercial Camera Company, Providence, R.I.) whose name became a generic noun and verb (1914) for "photocopy;" from photo- + -stat.

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cahoots (n.)

"company, partnership," 1829, Southern and Western American English, of unknown origin; said [OED] to be perhaps from French cahute "cabin, hut" (12c.), but U.S. sources [Bartlett] credit it to French cohorte (see cohort), which is said to have had a sense of "companions, confederates."

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accredit (v.)

1610s, "vouch for, bring into credit," from French accréditer, earlier acrediter, from à "to" (see ad-) + créditer "to credit" (someone with a sum), from crédit "credit" (see credit (n.)). Falsely Latinized in French. The word was rare in English in the original sense but became common in the meaning "confer credit or authority on" (1794). Related: Accredited; accrediting.

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Shinola (n.)

brand of shoe polish, by 1904, from shine in the "shoeshine" sense + commercial suffix -ola. The company that made it dates to 1877 and seems to have ceased production c. 1960, but by then the word was proverbial for what you don't know something isn't.

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