The time interval between the instant of the occurrence of a specified input condition to a system and the instant of completion of a specified operation.

(mathematics) An operation, written using the symbol +, that produces the sum of two operands

(mathematics) An operation of an algebraic structure playing a role analogous to multiplication.

(psychology) A technique of behavior modification through positive and negative reinforcement and positive and negative punishment.

(mathematics, physics) A differential operator,denoted ∆ and defined on ℝⁿ as 𝛥=∑ᵢ₌₁ⁿ(∂²)/(∂x_i²), used in the modeling of wave propagation, heat flow and many other applications.

A person who operates a telephone switchboard. / A person who provides assistance in establishing a connection, or who provides information or takes messages via the telephone.

A company that sells package holidays.

(finance) Negative operating income.

(UK) Alternative spelling of cooperate

(business, accounting) Any expense incurred in running a business, such as sales and administration, as opposed to production.