a payment made by feudal vassals to their lord on special occasions.
10.
English History. (after 1066) any of several revenues received by a king in the Middle Ages from his vassals and other subjects, limited by the Magna Charta to specified occasions.
Origin: 1375–1425; (noun) late Middle English ayde < Anglo-French, Old French aide, noun derivative of aid(i)er < Latin adjūtāre to help (frequentative of adjuvāre), equivalent to ad-ad- + -jū- help + -t- frequentative suffix + -āre infinitive suffix; (v.) < Anglo-French, Old French aid(i)er < Latin, as above
Usage note Although the nouns aid and aide both have among their meanings “an assisting person,” the spelling aide is increasingly used for the sense “helper, assistant”: One of the senator's aides is calling. Aide in military use is short for aide-de-camp. It is also the spelling in nurse's aide.