Tact
A verbal operant where the speaker names or describes something they perceive in the environment - controlled by what is seen, heard, or experienced rather than by what the speaker wants.
A tact is a verbal operant controlled by something in the environment. The learner sees, hears, or experiences something, and that sensory contact is what occasions the verbal response. Pointing to a dog and saying 'dog' is a tact. Saying 'it smells like lunch' is a tact. The form of the response doesn't matter - spoken, signed, typed, or selected on a device - what makes it a tact is that a nonverbal stimulus brought it out.
This is what distinguishes tacts from mands. A mand is controlled by what the learner wants. A tact is controlled by what the learner perceives. The same word can function as either. 'Water' because you're thirsty is a mand. 'Water' because someone points to a glass is a tact.
Tacts are the foundation of descriptive language - the ability to share experience with other people rather than just request things. A common error in teaching is conflating tact training with receptive identification. 'What is it?' teaches the tact. 'Touch the dog' tests receptive labelling. Both matter, but they require different instructional procedures.