The Collaborative International Dictionary of English v.0.48:
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
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
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.