When we say that a speaker uses a word to “refer” to an object, we are usually talking about a tact relationship. To say that a word refers to something often simply means that the word is a response controlled by a non-verbal discriminative stimulus.
A form of verbal behavior with the following features:
A verbal response
The controlling variable is a non-verbal stimulus, which is an object or event or a property of an object or event
The musculature with which the response is executed (vocal, written, gestural, etc.)
The modality of the stimulus (auditory, visual, gustatory, olfactory, etc.)
Whether or not there is any reinforcement for the current response
The “correctness” of the response