Final answer:
CR stands for Conditioned Response in classical conditioning and signifies a learned reaction to a stimulus that was previously neutral.
Step-by-step explanation:
The term CR, in the context of classical conditioning, stands for Conditioned Response. This is the learned response to the previously neutral stimulus that, after becoming associated with the unconditioned stimulus (UCS), now triggers a conditioned response similar to the unconditioned response (UCR). For example, if John starts salivating when he begins preparing his food (the CS - Conditioned Stimulus), the salivation (CR) is triggered not by the food itself (which would be the UCR in response to the UCS), but by the preparation process that he has learned to associate with eating.