Source : Webster's Revised Unabridged Dictionary (1913)

Understanding \Un`der*stand"ing\, a.
   Knowing; intelligent; skillful; as, he is an understanding
   man.

Understanding \Un`der*stand"ing\, n.
   1. The act of one who understands a thing, in any sense of
      the verb; knowledge; discernment; comprehension;
      interpretation; explanation.

   2. An agreement of opinion or feeling; adjustment of
      differences; harmony; anything mutually understood or
      agreed upon; as, to come to an understanding with another.

            He hoped the loyalty of his subjects would concur
            with him in the preserving of a good understanding
            between him and his people.           --Clarendon.

   3. The power to understand; the intellectual faculty; the
      intelligence; the rational powers collectively conceived
      an designated; the higher capacities of the intellect; the
      power to distinguish truth from falsehood, and to adapt
      means to ends.

            There is a spirit in man; and the inspiration of the
            Almighty them understanding.          --Job xxxii.
                                                  8.

            The power of perception is that which we call the
            understanding. Perception, which we make the act of
            the understanding, is of three sorts: 1. The
            perception of ideas in our mind; 2. The perception
            of the signification of signs; 3. The perception of
            the connection or repugnancy, agreement or
            disagreement, that there is between any of our
            ideas. All these are attributed to the
            understanding, or perceptive power, though it be the
            two latter only that use allows us to say we
            understand.                           --Locke.

            In its wider acceptation, understanding is the
            entire power of perceiving an conceiving, exclusive
            of the sensibility: the power of dealing with the
            impressions of sense, and composing them into
            wholes, according to a law of unity; and in its most
            comprehensive meaning it includes even simple
            apprehension.                         --Coleridge.

   4. Specifically, the discursive faculty; the faculty of
      knowing by the medium or use of general conceptions or
      relations. In this sense it is contrasted with, and
      distinguished from, the reason.

            I use the term understanding, not for the noetic
            faculty, intellect proper, or place of principles,
            but for the dianoetic or discursive faculty in its
            widest signification, for the faculty of relations
            or comparisons; and thus in the meaning in which
            ``verstand'' is now employed by the Germans. --Sir
                                                  W. Hamilton.

   Syn: Sense; intelligence; perception. See {Sense}.

Understand \Un`der*stand"\ ([u^]n`d[~e]r*st[a^]nd"), v. t. [imp.
   & p. p. {Understood}, 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.

Source : WordNet®

understanding
     adj : characterized by understanding based on comprehension and
           discernment and empathy; "an understanding friend"

understanding
     n 1: the cognitive condition of someone who understands; "he has
          virtually no understanding of social cause and effect"
          [syn: {apprehension}, {discernment}, {savvy}]
     2: the statement (oral or written) of an exchange of promises;
        "they had an agreement that they would not interfere in
        each other's business"; "there was an understanding
        between management and the workers" [syn: {agreement}]
     3: an inclination to support or be loyal to or to agree with an
        opinion; "his sympathies were always with the underdog";
        "I knew I could count on his understanding" [syn: {sympathy}]
     4: the capacity for rational thought or inference or
        discrimination; "we are told that man is endowed with
        reason and capable of distinguishing good from evil" [syn:
         {reason}, {intellect}]