The word ‘Bisect’ in philately refers to a stamp which is cut into two ‘equal’ halves, both of which are used for postage and crucially each half of the bisect has a postage value of half the original face value of the stamp.
Often bisect stamps are used when there is a shortage of stamps of the value required, and thus the applicable rate is made up of bisect stamps. There are a few examples of where the stamps are divided into smaller fraction, but in general a Bisect is two halves.
The collecting and studying of Bisects is a fascinating area of philately and postal history and certain countries and issues are extraordinarily rare and on occasions they are applied but not accepted by the postal authorities. A very good example of this type of usage is a Romania registered cover sent in 1871 during Carol I reign with two Bisects 10b yellow-orange on cover, attempting to pre-pay the 25b letter rate plus 25b registration fee. The bisects were unaccepted for foreign mail and each were struck through with pen crosses and a single 10b then added to make the 50b total. This is a very rare example, and sold at auction in 2014 for EUR 42’000, at a David Feldman SA auction. Click on the hyperlink for scans of the front and back, as well as a full description.
Caption for item illustrated above:
1868 Empire Laureate 40c orange VERTICAL BISECT tied to fragment on the bisected side by “4595” numeral of Beugnies, with manuscript “Bon pour / 020” adjacent showing acceptance of the bisect as payment for 20c postage, very fine and very rare.