diagonal cross with arms of equal length is an extremely old sign.
Like , it has been found engraved on the walls of prehistoric caves in Europe. In early Chinese ideography it stood for the number 5.
As an Egyptian hieroglyph it meant to damage, divide, count, or break into parts.
Compare this with its use as multiplication sign from the beginning of the seventeenth century. The law of the polarity of meanings of elementary graphs applies.
The very similar is a rune used in some of the old Nordic rune alphabets. Its name is gif or geba, meaning gift, especially a gift from a chief to a loyal warrior or subject.
As a modern ideogram the diagonal cross has a wide spectrum of meanings from confrontation, annulment, cancellation, over opposing forces, hindrances, obstruction, to unknown, undecided, unsettled.
Here are a number of examples of the specific meanings of in different systems: a crossbreed between different species, varieties or races (in botany and biology), takes (chess), printing error (printing), I/we can not continue (ground-to-air emergency code), unknown number or multiply (mathematics), unknown person (Mr. X), and road obstruction (military).
The diagonal cross is sometimes used as a symbol for Christ, whose name in Greek begins with the Greek letter X. It also stands for the number 1,000 in ancient Greece, and even represented Chronos, the god of time, the planet Saturn and the god Saturn in Roman mythology.
When the diagonal cross appears as a closed or filled sign, , it becomes the cross of St. Andrew (refer to this sign in Group 28). According to tradition, St. Andrew was too humble to allow himself to be crucified on the same type of cross as Christ.
In everyday use over, or very close to another ideogram means that what it denotes no longer counts, is wrong, is forbidden, or is cancelled. Examples are the road sign and the washing sign , do not bleach (from , can be bleached).
In Sweden, is used by the armed forces on maps to denote that blasting or other type of destruction has been prepared.
In the French hobo or gypsy sign system means this apartment/house is a good project for a burglary. As an English hobo sign, it means don't knock here. As a Swedish boy-scout sign it is used with a similar meaning: don't take this road.
In seventeenth-century alchemy denoted talc.
In musical notation is called double cross.
See in Group 11 for more data.
The closed variation, , is found on some telephone answering machines indicating the control for the wiping out of taped messages.