The Collaborative International Dictionary of English v.0.48:

Verb \Verb\, n. [F. verbe, L. verbum a word, verb. See Word.]
   1. A word; a vocable. [Obs.] --South.
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   2. (Gram.) A word which affirms or predicates something of
      some person or thing; a part of speech expressing being,
      action, or the suffering of action.
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   Note: A verb is a word whereby the chief action of the mind
         [the assertion or the denial of a proposition] finds
         expression. --Earle.
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   Active verb, Auxiliary verb, Neuter verb, etc. See
      Active, Auxiliary, Neuter, etc.
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The Collaborative International Dictionary of English v.0.48:

Auxiliary \Aux*il"ia*ry\, n.; pl. Auxiliaries.
   1. A helper; an assistant; a confederate in some action or
      enterprise.
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   2. (Mil.) pl. Foreign troops in the service of a nation at
      war; (rarely in sing.), a member of the allied or
      subsidiary force.
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   3. (Gram.) A verb which helps to form the voices, modes, and
      tenses of other verbs; -- called, also, an auxiliary
      verb; as, have, be, may, can, do, must, shall, and will,
      in English; [^e]tre and avoir, in French; avere and
      essere, in Italian; estar and haber, in Spanish.
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   4. (Math.) A quantity introduced for the purpose of
      simplifying or facilitating some operation, as in
      equations or trigonometrical formul[ae]. --Math. Dict.
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WordNet (r) 3.0 (2006):

auxiliary verb
    n 1: a verb that combines with another verb in a verb phrase to
         help form tense, mood, voice, or condition of the verb it
         combines with