The Collaborative International Dictionary of English v.0.48:

Assert \As*sert"\, v. t. [imp. & p. p. Asserted; p. pr. & vb.
   n. Asserting.] [L. assertus, p. p. of asserere to join or
   fasten to one's self, claim, maintain; ad + serere to join or
   bind together. See Series.]
   1. To affirm; to declare with assurance, or plainly and
      strongly; to state positively; to aver; to asseverate.
      [1913 Webster]

            Nothing is more shameful . . . than to assert
            anything to be done without a cause.  --Ray.
      [1913 Webster]

   2. To maintain; to defend. [Obs. or Archaic]
      [1913 Webster]

            That . . . I may assert Eternal Providence,
            And justify the ways of God to men.   --Milton.
      [1913 Webster]

            I will assert it from the scandal.    --Jer. Taylor.
      [1913 Webster]

   3. To maintain or defend, as a cause or a claim, by words or
      measures; to vindicate a claim or title to; as, to assert
      our rights and liberties.
      [1913 Webster]

   To assert one's self, to claim or vindicate one's rights or
      position; to demand recognition.
      [1913 Webster]

   Syn: To affirm; aver; asseverate; maintain; protest;
        pronounce; declare; vindicate.

   Usage: To Assert, Affirm, Maintain, Vindicate. To
          assert is to fasten to one's self, and hence to claim.
          It is, therefore, adversative in its nature. We assert
          our rights and privileges, or the cause of tree
          institutions, as against opposition or denial. To
          affirm is to declare as true. We assert boldly; we
          affirm positively. To maintain is to uphold, and
          insist upon with earnestness, whatever we have once
          asserted; as, to maintain one's cause, to maintain an
          argument, to maintain the ground we have taken. To
          vindicate is to use language and measures of the
          strongest kind, in defense of ourselves and those for
          whom we act. We maintain our assertions by adducing
          proofs, facts, or arguments; we are ready to vindicate
          our rights or interests by the utmost exertion of our
          powers.
          [1913 Webster]

WordNet (r) 3.0 (2006):

assert
    v 1: state categorically [syn: assert, asseverate,
         maintain]
    2: to declare or affirm solemnly and formally as true; "Before
       God I swear I am innocent" [syn: affirm, verify,
       assert, avow, aver, swan, swear]
    3: insist on having one's opinions and rights recognized; "Women
       should assert themselves more!" [syn: assert, put
       forward]
    4: assert to be true; "The letter asserts a free society" [syn:
       insist, assert]

Moby Thesaurus II by Grady Ward, 1.0:

86 Moby Thesaurus words for "assert":
   advance, advocate, affirm, allege, allege in support, announce,
   annunciate, answer, argue, argue for, assever, asseverate, aver,
   avouch, avow, brook no denial, champion, confess, contend,
   contend for, counter, declare, defend, enunciate, espouse, express,
   express the belief, have, hold, insist, insist on, insist upon,
   issue a manifesto, lay down, maintain, make a plea, manifesto,
   nuncupate, persist, plead for, pose, posit, postulate, predicate,
   press, proclaim, profess, pronounce, propose, propound, protest,
   put, put it, quote, rebut, recite, refute, relate, reply, respond,
   riposte, say, say in defense, set down, set forth, speak,
   speak for, speak out, speak up, speak up for, stand for, stand on,
   stand up for, state, stick to, stick up for, submit, support,
   sustain, swear, take no denial, uphold, urge, urge reasons for,
   vow, warrant



V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

ASSERT
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