: to cause oneself to become unconscious
He hit his head against the table when he fell and knocked himself out.
informal : to make oneself very tired by doing work
I knocked myself out to get the job done on time.
US —used to tell someone to go ahead and do something
"Do you mind if I use this exercise machine first?" "Knock yourself out."
Love words? Need even more definitions?Merriam-Webster unabridged