What is "to give one to understand"

Understand \Un`der*stand"\ ([u^]n`d[~e]r*st[a^]nd"), v. t. [imp. & p. p. Understood (([u^]n`d[~e]r*st[oo^]d"),), and Archaic Understanded; p. pr. & vb. n. Understanding.] [OE. understanden, AS. understandan, literally, to stand under; cf. AS. forstandan to understand, G. verstehen. The development of sense is not clear. See Under, and Stand.]

1. To have just and adequate ideas of; to apprehended the meaning or intention of; to have knowledge of; to comprehend; to know; as, to understand a problem in Euclid; to understand a proposition or a declaration; the court understands the advocate or his argument; to understand the sacred oracles; to understand a nod or a wink.

   Speaketh [i. e., speak thou] so plain at this time, I you pray, That we may understande what ye say.
   --Chaucer.

   I understand not what you mean by this.
   --Shak.

   Understood not all was but a show.
   --Milton.

   A tongue not understanded of the people.
   --Bk. of Com. Prayer.

2. To be apprised, or have information, of; to learn; to be informed of; to hear; as, I understand that Congress has passed the bill.

3. To recognize or hold as being or signifying; to suppose to mean; to interpret; to explain.

   The most learned interpreters understood the words of sin, and not of Abel.
   --Locke.

4. To mean without expressing; to imply tacitly; to take for granted; to assume.

   War, then, war, Open or understood, must be resolved.
   --Milton.

5. To stand under; to support. [Jocose & R.]
   --Shak.

   To give one to understand, to cause one to know.

   To make one's self understood, to make one's meaning clear.