shutdown
noun
Definitions
The action of stopping operations; a closing, of a computer, business, event, etc.
Example: You need to enter your password at startup, but it's not required at shutdown.
A statement, insult, etc. that prevents the opponent from replying further.
Example: When he insulted me, my reply was such a shutdown that he left the room.
An autistic response to stress, etc. where the individual becomes silent and motionless.