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. To assert one's self, to claim or vindicate one's rights or position; to demand recognition.
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.
Source: Websters Dictiona 3c6 ry