knock out

动词 Verb

To strike or render unconscious
(transitive) To communicate (a message) by knocking.
(transitive, informal) To complete, especially in haste; knock off.
To lose the scent of hounds in fox-hunting.
(obsolete, Oxford University slang) To leave college after hours—after half-past ten at night when the doors have been locked.
(transitive, Australia) To obtain or earn (something, often money or food).
(transitive, slang, UK) To sell.

派生词（3）