The square in a horizontal-vertical position
is an expression of the two dimensions that constitute a
surface. Basically means land, field, ground, or the element earth. The Egyptians used it, originally as a pictorial
sign for stool of reed matting.
For the alchemists the square could represent salt. Salt was often produced by letting sea water evaporate on the ground. Even in modern meteorology can represent the ground. The sign placed within the square indicates the weather's effect on the ground, as in , ground covered with snow. In Diderot's Encyclopedia it is recorded as a sign for magnet.
The ground-to-air emergency code also relates this structure to the ground or the land: compass and map needed. Its association to the ground is also seen in the use of and on maps for farm or farmhouse.
In astrology signifies the most difficult and tense aspect that can occur between two planets in a natal chart. This spect is called the square, the angle of 90 degrees.
Botanists sometimes use it to denote the male individual of dioecious plants (in which case stands for the female). In military contexts the sign can be used for private soldiers.
The filled square, , appears on videotape recorders for the control for interrupting recording or play.
Last, it should be mentioned that squares with lines in them occur in garments to indicate how the garment should be treated in washing. Thus, for instance, means that the garment can be drip-dried.