VERB (3)

1. impart knowledge of some fact, state or affairs, or event to;
- Example: "I informed him of his rights"

2. give character or essence to;
- Example: "The principles that inform modern teaching"

3. act as an informer;
- Example: "She had informed on her own parents for years"

The Collaborative International Dictionary of English v.0.48:

Inform \In*form"\, a. [L. informis; pref. in- not + forma form,
   shape: cf. F. informe]
   Without regular form; shapeless; ugly; deformed. --Cotton.
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The Collaborative International Dictionary of English v.0.48:

Inform \In*form"\, v. t.
   1. To take form; to become visible or manifest; to appear.
      [Obs.]
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            It is the bloody business which informs
            Thus to mine eyes.                    --Shak.
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   2. To give intelligence or information; to tell. --Shak.
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            He might either teach in the same manner, or inform
            how he had been taught.               --Monthly Rev.
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   To inform against, to communicate facts by way of
      accusation against; to denounce; as, two persons came to
      the magistrate, and informed against A.
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The Collaborative International Dictionary of English v.0.48:

Inform \In*form"\, v. t. [imp. & p. p. Informed; p. pr. & vb.
   n. Informing.] [OE. enformen, OF. enformer, F. informer. L.
   informare; pref. in- in + formare to form, share, fr. forma
   form. See Form.]
   1. To give form or share to; to give vital or organizing
      power to; to give life to; to imbue and actuate with
      vitality; to animate; to mold; to figure; to fashion. "The
      informing Word."                            --Coleridge.
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            Let others better mold the running mass
            Of metals, and inform the breathing brass. --Dryden.
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            Breath informs this fleeting frame.   --Prior.
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            Breathes in our soul, informs our mortal part.
                                                  --Pope.
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   2. To communicate knowledge to; to make known to; to
      acquaint; to advise; to instruct; to tell; to notify; to
      enlighten; -- usually followed by of.
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            For he would learn their business secretly,
            And then inform his master hastily.   --Spenser.
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            I am informed thoroughly of the cause. --Shak.
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   3. To communicate a knowledge of facts to, by way of
      accusation; to warn against anybody.
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            Tertullus . . . informed the governor against Paul.
                                                  --Acts xxiv.
                                                  1.

   Syn: To acquaint; apprise; tell; teach; instruct; enlighten;
        animate; fashion.
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WordNet (r) 3.0 (2006):

inform
    v 1: impart knowledge of some fact, state or affairs, or event
         to; "I informed him of his rights"
    2: give character or essence to; "The principles that inform
       modern teaching"
    3: act as an informer; "She had informed on her own parents for
       years"

Moby Thesaurus II by Grady Ward, 1.0:

124 Moby Thesaurus words for "inform":
   acquaint, advertise, advertise of, advise, animate, announce,
   apprise, babble, be indiscreet, be unguarded, betray,
   betray a confidence, blab, blabber, blurt, blurt out,
   break the news, brief, bring word, broaden the mind, catechize,
   civilize, communicate, demonstrate, direct, disclose, divulge, due,
   edify, educate, embue, endow, endue, enlighten, enliven, exalt,
   exhilarate, familiarize, fill in, finger, fire, forewarn,
   give a report, give away, give instruction, give lessons in,
   give notice, give the facts, give tidings of, give word, ground,
   guide, identify, illuminate, illumine, imbue, impart, implicate,
   incriminate, infect, inform on, infuse, inject, inoculate, inspire,
   inspirit, instruct, keep posted, leak, leave word, leaven,
   let drop, let fall, let know, let slip, mention to, nark, notify,
   open the eyes, peach, permeate, pimp, post, rat, reeducate,
   rehearse, relate, report, reveal, reveal a secret, rumor, school,
   send word, serve notice, set right, sharpen the wits, show,
   show how, sing, snitch, snitch on, speak, spill, spill the beans,
   spirit, spirit up, squeak, squeal, stool, talk, tattle, tattle on,
   teach, teach a lesson, teach the rudiments, tell, tell on,
   tell secrets, tell tales, tip off, turn in, verse, warn,
   write up