A bisector, which divides into two equal parts.
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.
To divide an angle, line segment, or other figure into two equal parts.
To perform a binary search on files in source control in order to identify the specific change that introduced a bug etc.
Double.
Having two beats in each foot.
Having two beats, or a multiple of two beats, in each measure.