What does "aid" mean?

Additional senses

1. 2.The person or thing that promotes or helps in something done; a helper; an assistant. It is not good that man should be alone; let us make unto him an aid like unto himself. Tobit viii.
2. 3.3. (Eng. Hist.) A subsidy granted to the king by Parliament; also, an exchequer loan.
3. 4.(Feudal Law) A pecuniary tribute paid by a vassal to his lord on special occasions. Blackstone.
4. 5.An aid-de-camp, so called by abbreviation; as, a general's aid. Aid prayer (Law), a proceeding by which a defendant beseeches and claims assistance from some one who has a further or more permanent interest in the matter in suit. -- To pray in aid, to beseech and claim such assistance.