Source : Webster's Revised Unabridged Dictionary (1913)

Aid \Aid\, n. [F. aide, OF. a["i]de, a["i]e, fr. the verb. See
   {Aid}, v. t.]
   1. Help; succor; assistance; relief.

            An unconstitutional mode of obtaining aid. --Hallam.

   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.
                                                  6.

   3. (Eng. Hist.) A subsidy granted to the king by Parliament;
      also, an exchequer loan.

   4. (Feudal Law) A pecuniary tribute paid by a vassal to his
      lord on special occasions. --Blackstone.

   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.