(mathematics) the symbol ±, meaning "plus or minus", used to indicate the precision of an approximation (as in "The result is 10 ± 0.3", meaning the result is anywhere in the inclusive range from 9.7 to 10.3), or as a convenient shorthand for a quantity with two possible values of opposing sign and identical magnitude (as in "The roots of the equation x² - 4 = 0 are ±2").

(intransitive, idiomatic) To formalize an agreement.

(mathematics) the symbol ∓, meaning "minus or plus", used alongside the plus-minus sign to show that a negative value is to be taken where the positive value is indicated by the plus-minus sign, and vice versa (as in (x ± 1) / (x ∓ 2), which means (x + 1) / (x - 2) and (x - 1) / (x + 2)).

(military) A call sign assigned in accordance with the provisions of the International Telecommunications Union to identify a radio station. The nationality of the radio station is identified by the first or the first two characters. (When used in visual signaling, international call signs are referred to as “signal letters.”)

(military) A call sign which does not represent a specific facility, command, authority, activity, or unit, but which may represent any one or any group of these.

(military) Any call sign which represents two or more facilities, commands, authorities, or units. The collective call sign for any of these includes the commander thereof and all subordinate commanders therein.

(military) A call sign that represents all stations within a net.

(military) A call sign that identifies a tactical command or tactical communication facility.

A written representation for numbers consisting of a series of numeric signs whose values, added together, yield the number represented.

A local indigenous sign language in an area with a high incidence of congenital deafness.