(informal) An interpretation sign.

A public sign at a historical site, nature reserve, etc., that provides information, facts, and figures for the benefit of visitors.

A language that uses hands, facial expressions, and other bodily behavior to communicate both concrete and abstract ideas; some signs are based on English words, but ASL syntax and grammar are not based on English. ISO 639-3 code: ase.

(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").

(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)).

(intransitive, idiomatic) To formalize an agreement.

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

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

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