The Collaborative International Dictionary of English v.0.48:

Teach \Teach\ (t[=e]ch), v. t. [imp. & p. p. Taught (t[add]t);
   p. pr. & vb. n. Teaching.] [OE. techen, imp. taughte,
   tahte, AS. t[=ae]cean, imp. t[=ae]hte, to show, teach, akin
   to t[=a]cn token. See Token.]
   1. To impart the knowledge of; to give intelligence
      concerning; to impart, as knowledge before unknown, or
      rules for practice; to inculcate as true or important; to
      exhibit impressively; as, to teach arithmetic, dancing,
      music, or the like; to teach morals.
      [1913 Webster]

            If some men teach wicked things, it must be that
            others should practice them.          --South.
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   2. To direct, as an instructor; to manage, as a preceptor; to
      guide the studies of; to instruct; to inform; to conduct
      through a course of studies; as, to teach a child or a
      class. "He taught his disciples." --Mark ix. 31.
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            The village master taught his little school.
                                                  --Goldsmith.
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   3. To accustom; to guide; to show; to admonish.
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            I shall myself to herbs teach you.    --Chaucer.
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            They have taught their tongue to speak lies. --Jer.
                                                  ix. 5.
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   Note: This verb is often used with two objects, one of the
         person, the other of the thing; as, he taught me Latin
         grammar. In the passive construction, either of these
         objects may be retained in the objective case, while
         the other becomes the subject; as, I was taught Latin
         grammar by him; Latin grammar was taught me by him.
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   Syn: To instruct; inform; inculcate; tell; guide; counsel;
        admonish. See the Note under Learn.
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The Collaborative International Dictionary of English v.0.48:

Teaching \Teach"ing\, n.
   The act or business of instructing; also, that which is
   taught; instruction.
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   Syn: Education; instruction; breeding. See Education.
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WordNet (r) 3.0 (2006):

teaching
    n 1: the profession of a teacher; "he prepared for teaching
         while still in college"; "pedagogy is recognized as an
         important profession" [syn: teaching, instruction,
         pedagogy]
    2: a doctrine that is taught; "the teachings of religion"; "he
       believed all the Christian precepts" [syn: teaching,
       precept, commandment]
    3: the activities of educating or instructing; activities that
       impart knowledge or skill; "he received no formal education";
       "our instruction was carefully programmed"; "good classroom
       teaching is seldom rewarded" [syn: education,
       instruction, teaching, pedagogy, didactics,
       educational activity]