Plus–minus sign

The plus–minus sign, ±, is a mathematical symbol with multiple meanings:

• In mathematics, it generally indicates a choice of exactly two possible values, one of which is obtained through addition and the other through subtraction.
• In experimental sciences, the sign commonly indicates the confidence interval or uncertainty bounding a range of possible errors in a measurement, often the standard deviation or standard error. The sign may also represent an inclusive range of values that a reading might have.
• In medicine, it may mean "with or without" in some cases.
• In engineering, the sign indicates the tolerance, which is the range of values that are considered to be acceptable or safe, or which comply with some standard or with a contract.
• In botany, it is used in morphological descriptions to notate "more or less".
• In chemistry, the sign is used to indicate a racemic mixture.
• In chess, the sign indicates a clear advantage for the white player; the complementary minus-plus sign, ∓, indicates the same advantage for the black player.
• In electronics, this sign may indicate a dual voltage power supply, such as ±5 volts means +5 volts and −5 volts, when used with audio circuits and operational amplifiers.
• In linguistics, it may indicate a distinctive feature, such as [±voiced].
• In philosophy, the symbol ± or ∓ can be used to indicate a yinyang concept. Although Yin(-) and Yang(+) are in opposition, they coordinate and help each other in a unity. Yin and Yang are interdependent and coexist as two sides of the same concept.