Give or take
Patriarchal Cross
Altar Cross
This is similar to the Altar Cross, with a base for standing on a table, and vaguely similar properties to an inverted Patriarchal Cross, but the symbol on the left has its own meaning.
It's most commonly used as a ± sign in mathematics, meaning "plus or minus", or less mathematically, "give or take". Sometimes there's a gap between the + and the _, depending on the handwriting style, or in the case of printing, the font.
As with the individual plus and minus symbols, the combined (±) symbol is not ancient, but not as modern as claimed by Webster's online dictionary: "first known use: 1971". No, it's older than that. It's probably 400 years old, ± 100 years.
The ± symbol was used in a textbook by the English mathematician Rev. William Oughtred (1574-1660) written for the benefit of his tutee, the son of the Earl of Arundel, and published as Clavis Mathematicae (The Key to Mathematics) in 1631.
A complementary symbol (mainly used in mathematics) is ∓. This symbol is rarely seen and although the game of chess is not intended to be racist, it's interesting that the more common ± means the advantage for white over black, and ∓ means the advantage for black over white.
Two symbols comparable to ± are found in Chinese and Japanese script, where the upper and lower horizontal beams have slightly different lengths. When the lower beam is longer than the upper beam, the character means earth/soil/ground, originally a pictograph of a clod of earth. (No, I can't see a clod of earth there either, but that's what it is. )
When the upper beam is longer than the lower beam, the character means gentleman/soldier/samurai, symbolising the male organ with glans, the epitome of masculinity and supremacy.
As with many symbols, these meanings can be Christianized:
- Where in mathematics, the ± and ∓ symbols mean tolerance, in Christ the cross means forgiveness;
- take the love and salvation that Christ offers to give us;
- the positive over the negative (±), the triumph of love over evil.
- And from the related Asian characters,
- the earth representing the solid rock or foundation of the church;
- and the supremacy of Christ.
For example, a healthy person's internal body temperature is 37.0 °C ± 0.5 °C. That is, a temperature anywhere between 36.5 °C and 37.5 °C is considered normal. The actual temperature depends on the part of the body being measured, time of day, ambient temperature, recent activities, etc.
See examples on pages 50-52 of Clavis Mathematicae on Google Books, where its meaning is explained by maius/minus (more/less), and further on pages 76, 83, 86. The same book also shows early uses of the St Andrew's X symbol for multiplication and parallel lines of equal length to make an elongated = sign.
A Guide to Remembering Japanese Characters, p. 17, Kenneth G Henshall, Tuttle Language Library, 1988
