1) An intraverbal is a class of verbal operants regulated by verbal discriminative stimuli. In everyday language, thematically related words (or sentences) are examples of intraverbals. For example, the verbal response "fish" to the spoken words "rod and reel" is an intraverbal; saying "water" to the written word lake is also intraverbal behavior. Thus, intraverbal stimuli arise from verbal behavior; a previous verbal response by a speaker is a stimulus for a subsequent verbal operant.

2) A class of verbal operants whose form is regulated by specific nonverbal discriminative stimuli. For example, a child may see a cat and say, "Look mom, a kitty." The word tact comes from the more familiar term contact. Tacts are verbal responses that make contact with the environment.

3) A verbal discriminative response (as when the verbal response apple in the presence of an apple is said to tact the apple). The tact captures stimulus control as it enters into verbal behavior. The tact relation includes only responses in the presence of or shortly after a stimulus, and therefore is not equivalent to naming or reference.