salary

Middle English salarie, salaire "compensation, payment," borrowed from Anglo-French (also continental Old French), borrowed from Latin salārium "official pay given to the holder of a civil or military post," noun derivative from neuter of salārius "of or relating to salt," from sal-, sāl "salt" + -ārius -ary entry 2 — more at salt entry 1

Note: The notion that Latin salārium originally referred to money given to Roman soldiers to buy salt is a popular one, but it has no basis in ancient sources. It rests on the inference that salārium was originally short for an unattested phrase salārium argentum "salt money," which would have been parallel to the contextually better attested words calceārium "money for shoes" (from calceus "shoe") or vestiārium "allowance in money or kind to provide for clothing" (from vestis "clothes"). The inference can be found in Charlton Lewis and Charles Short's A Latin Dictionary (1879), many times reprinted, though it was copied from earlier dictionaries, as the Latin-German dictionaries of Wilhelm Freund (1840) and I.J.G. Scheller (1783) (Scheller, however, takes dōnum "gift, prize" to have been the understood word). Pliny the Elder has been cited as support for the soldier's pay explanation, though the text of his Historia naturalis refers only to some undefined role salt paid in relation to honors in war, "from which the word salārium is derived" ("[sal] honoribus etiam militiaeque interponitur salariis inde dictis"; 31.89). As Pliny is extolling the virtues of salt in this chapter, it seems likely that if he knew of a better explanation for the word, he would have mentioned it. Clearly salt was somehow involved in the notion of official compensation in early imperial Rome, but to speculate further on its function is no more than guessing. (Compare "Salt and salary: were Roman soldiers paid in salt?," blog post by New Zealand classicist Peter Gainsford, Kiwi Hellenist, January 11, 2017, available online 5/26/22.)