in a general sense, denotes any kind of assistance given by one person to another.

in Law, denotes a petition made in court to call in help from another person who has interest in land, or anything contested.

Aid-de-Camp, in military affairs, an officer employed to receive and carry the orders of a general.

Auxilium, in ancient customs, a subsidy paid by vassals to their lords on certain occasions. Such were the aid of relief, paid upon the death of the lord next to his heir; the aid cheval, or capital aid, due to the chief lord on several occasions, as, to make his elder son a knight, to make up a portion for marrying his daughter, &c.