1.
To knock someone out means to cause them to become unconscious or to go to sleep.
The three drinks knocked him out...
He had never been knocked out in a professional fight.
PHRASAL VERB : V n P , V n P , also V P n (not pron)
2.
If a person or team is knocked out of a competition, they are defeated in a game, so that they take no more part in the competition.
Henri Leconte has been knocked out in the quarter-finals of the Geneva Open...
The Irish came so close to knocking England out of the European Championships.
PHRASAL VERB : be V-ed P , V n P of n , also V P n
see also knockout
3.
If something is knocked out by enemy action or bad weather, it is destroyed or stops functioning because of it.
Our bombers have knocked out the mobile launchers...
PHRASAL VERB : V P n (not pron)