What is "to pray in aid"

Pray \Pray\, v. t.

1. To address earnest request to; to supplicate; to entreat; to implore; to beseech.

   And as this earl was preyed, so did he.
   --Chaucer.

   We pray you . . . by ye reconciled to God.
   --2 Cor. v. 20.

2. To ask earnestly for; to seek to obtain by supplication; to entreat for.

   I know not how to pray your patience.
   --Shak.

3. To effect or accomplish by praying; as, to pray a soul out of purgatory. --Milman. To pray in aid. (Law)

   1. To call in as a helper one who has an interest in the cause.
      --Bacon.

   2. A phrase often used to signify claiming the benefit of an argument. See under Aid.
      --Mozley & W.

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.