assert

uh-SURTverb

Meaning to state something firmly and confidently

Memory hook a SERGEANT doesn’t ask: he ASSERTS. “We march at dawn!” the sergeant says, firm and sure, without a trace of doubt. He doesn’t ask; he asserts.

Zoe asserted that her cat could open doors, and then the cat did.

In context The author does not merely suggest that sleep helps memory; she asserts it plainly in the first sentence and spends the chapter backing it up.

Similar declare, affirm, state, insist

Opposite deny, retract

From Latin asserere, “to claim, declare”: ad (to) + serere (to join).