When the cross appears within a circle but free from it, i.e. not
touching the circumference, a new spectrum of meaning prevails. It
becomes a positive sign, a plus, and the circle now signifies a
closed unit of space or time. Thus in the British system of
hobo signs means here you will get a day's
work. In a technical context it can mean rising
pressure (in a
tank or something similar). With an arrow added to denote a
directed movement, , it becomes a chemical
sign for positive ions. Even without the arrow it can denote positive ions,
As a sign in physics signifies a proton or positron, i.e. a small, positively charged unit in the atom.
In the Catholic Christianity this sign is a symbol for the Eucharist (the blessed wafer handed out to Catholics at the Mass).
Sometimes is given the same meaning as , and in such instances should be viewed as a stylized version of .
This sign was in use already 5,000 years ago by the Sumerians. It is said to have meant sheep. For the Aztecs was known as the shield of the God of Dawn.
See also in Group 32.