Inclined to bold or confident assertion; aggressively self-assured.(adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "assertive" in a sentence
"In its annual defense white paper, released Tuesday, the Japanese government for the first time used the word "assertive" in describing China's behavior toward its neighbors."
"Patterson seems like a decent fellow, but lacking in assertive leadership skills."
"Billups was assertive from the start, instead of deferring to teammates as he usually does early in games."