accountant n.

c. 1300, accounten, "to count, enumerate," from Old French aconter "to enumerate; reckon up, render account" (Modern French conter), from a "to" (see ad-) + conter "to count, tell" (see count (v.)).

The meaning "reckon for money given or received, render a reckoning," is from late 14c. The sense of "to explain, justify" (c. 1300) is from the notion of "present a detailed explanation of money, etc. held in trust." The transferred sense of "to value, to estimate" (to account as belonging to a certain of quality) is from late 14c. The intransitive sense of "render an account of particulars" is from late 14c.; hence the transitive sense "give an explanation" (1670s, which usually takes to before a person and for before a thing).

In later Old French the word was partly re-Latinized as acompter (Modern French accompter), hence late Middle English accompten. Related: Accounted; accounting.

"the art of the accountant," 1848, from accountant + abstract noun suffix -cy. Accountantship is attested by 1818.