The diagonally placed
square has no particular spectrum of meaning as far as we know. It
is found engraved in the cave of Marsoulas in prehistoric times, but
there are no clues as to what it might have meant. The sign is the symbol for the suit of
diamonds in a pack of
cards. Diamonds are usually associated with courage and
The British hobos made use of to mean here live generous people, but behave well, show them respect, and take nothing for granted. In the French hobo or gypsy sign system means here nobody lives.
In meteorology it can sometimes signify clear air and in chemistry, soft soap. It has been used in biological contexts for an individual of unknown or not stated sex.
In North America, Japan and Australia (at least) it is a road sign meaning danger ahead.
Compare with , one of the alchemists' signs for sulphur and also one of the signs for the asteroid Pallas.