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.

That operates to produce an effect.

An operative person or thing. / (psychology) Any of a class of behaviors that produce consequences by operating (i.e., acting) upon the environment.

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

(transitive or intransitive) To perform a work or labour; to exert power or strength, physical or mechanical; to act.

Of, related to, or typical of opera.

A lever, key or device installed in a operant chamber, upon which the "subject" exerts its responses. Sometimes referred to as a manipulandum. In the prototypical operant conditioning experiment, a rat (the subject) presses upon a lever (the operandum) which triggers the delivery of food (the reward or reinforcer).

(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.