(geometry) A bisector, which divides into two equal parts.

(philately) An envelope, card, or fragment thereof showing an affixed cut half of a regular issued stamp, over which one or more postal markings have been applied. Typically used in wartime when normal lower rate stamps may not be available.

Cut or divide something into two equal parts, such as an angle, line segment, or figure, and can also refer to performing a binary search on files in source control to identify a specific change.