close out

Verb

 * 1)  To terminate; to call the end of.
 * 2)  Of a wave, to break all at once, instead of progressively along its length.
 * 3)  To terminate a computer program.
 * 4)  To exclude by blocking all opportunities to enter or join.
 * 5)  To make trades offsetting an existing position, leaving the trader with a neutral position.
 * 6)  To seal off.
 * 1)  To terminate a computer program.
 * 2)  To exclude by blocking all opportunities to enter or join.
 * 3)  To make trades offsetting an existing position, leaving the trader with a neutral position.
 * 4)  To seal off.
 * 1)  To seal off.

Usage notes
In computing sense, and close out are both used, with close out being more informal, and more connotation of completely (as opposed to terminating a single window or document). Compare other computing phrasal verbs such as and.