Wordnet 3.0
NOUN (2)
1.
the act of putting forth your own opinions in a boastful or inconsiderate manner that implies you feel superior to others;
2.
the act of asserting yourself in an aggressive manner;
The Collaborative International Dictionary of English v.0.48:
Self-assertion \Self`-as*ser"tion\, n.
The act of asserting one's self, or one's own rights or
claims; the quality of being self-asserting.
[1913 Webster]
WordNet (r) 3.0 (2006):
self-assertion
n 1: the act of putting forth your own opinions in a boastful or
inconsiderate manner that implies you feel superior to
others
2: the act of asserting yourself in an aggressive manner