assert · verb /əˈsɜrt/
assert
C1 T to say that something is certainly true
Dictionary example:
He asserts that she stole money from him.
Learner example:
It could be asserted that less financially able children are better equipped to cope with potential life problems than the more fortunate children. (International English Language Testing System; C1; Thai)
assert yourself
C2 to behave or speak in a strong, confident way
Dictionary example:
She has to learn to assert herself.
Learner example:
Such an attitude may also be the result of little pangs of homesickness or of our need to assert ourselves, to feel superior in a foreign country. (Certificate of Proficiency in English; C2; French)
assert your authority/control/independence, etc.
C2 to do something to show other people that you have power
Dictionary example:
She soon asserted her authority as leader.
Learner example:
He can assert his authority over all the boys who are there. (Certificate of Proficiency in English; C2; Italian)