early 15c., "action of certifying," from French certificat, from Medieval Latin certificatum "thing certified," noun use of neuter past participle of certificare "to make certain" (see certify). Of documents of certification, testifying to the truth of the facts stated, from mid-15c.; especially a signed document attesting to someone's authorization to practice or do stated things (1540s).
1620s, "place in the hands of another as a pledge for a contract," from Latin depositus, past participle of deponere "lay aside, put down, deposit," also used of births and bets, from de "away" (see de-) + ponere "to put, place" (past participle positus; see position (n.)). From 1650s as "lay away for safe-keeping;" from 1749 as "lay down, place, put." Related: Deposited; depositing.
1620s, "state of being placed in safe-keeping," from Latin depositum, from deponere (see deposit (v.)). From 1660s as "that which is laid or thrown down." Geological sense is from 1781; financial sense "money lodged in a bank for safety or convenience" is from 1737. Middle English had depost "thing entrusted for safe-keeping" (late 14c.).
1979 as an abbreviation of compact disc as a digital system of information storage. By 1959 as an abbreviation of certificate of deposit "written statement from a bank acknowledging it has received a sum of money from the person named" (1819).
"licensed or authorized by certificate," 1610s, past-participle adjective from obsolete certificate (v.) "furnish (someone) with a certificate," from Medieval Latin certificatus, past participle of certificare "to make certain" (see certify).
1795, "warehouse or storehouse for receiving goods for storage, sale, or transfer," from French dépôt "a deposit, place of deposit," from Old French depost "a deposit or pledge," from Latin depositum "a deposit," noun use of neuter past participle of deponere "lay aside, put down," from de "away" (see de-) + ponere "to put, place" (past participle positus; see position (n.)).
Military sense of "fort where stores, ammunition, etc. are deposited" is from 1798; meaning "railway station, building for accommodation and shelter of passengers and the receipt and transfer of freight" is attested by 1842, American English.
"attested by certificate," 1610s, past-participle adjective from certify. Certified public accountant attested from 1896; certified mail from 1955.