Definition of knock (something) on the head
- The closing of the airport knocked our holiday plans on the head.
: to strike something with a sharp blow
: to collide with something
: a sharp blow : rap, hit
: a severe misfortune or hardship
: setback, reversal
: some indeterminate or unspecified thing
: some indeterminate amount more than a specified number
: a person or thing of consequence
: in some degree : somewhat
used as an intensive giving adverbial force to an adjective
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