accredit (v.)

word-forming element expressing direction toward or in addition to, from Latin ad "to, toward" in space or time; "with regard to, in relation to," as a prefix, sometimes merely emphatic, from PIE root *ad- "to, near, at."

Simplified to a- before sc-, sp- and st-; modified to ac- before many consonants and then re-spelled af-, ag-, al-, etc., in conformity with the following consonant (as in affection, aggression). Also compare ap- (1).

In Old French, reduced to a- in all cases (an evolution already underway in Merovingian Latin), but French refashioned its written forms on the Latin model in 14c., and English did likewise 15c. in words it had picked up from Old French. In many cases pronunciation followed the shift.

Over-correction at the end of the Middle Ages in French and then English "restored" the -d- or a doubled consonant to some words that never had it (accursed, afford). The process went further in England than in France (where the vernacular sometimes resisted the pedantic), resulting in English adjourn, advance, address, advertisement (Modern French ajourner, avancer, adresser, avertissement). In modern word-formation sometimes ad- and ab- are regarded as opposites, but this was not in classical Latin.

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.