What substance is defined as having addiction-forming liability similar to morphine?

The correct answer, which identifies the substance as having addiction-forming liability similar to morphine, is opiate. Opiates are a class of drugs that are derived from opium poppy and include natural substances such as morphine and codeine. They are known for their ability to relieve pain and their potential for causing physical and psychological dependence.

Opiates share a biochemical structure and mechanism of action with morphine, targeting the same opioid receptors in the brain to produce similar effects, including analgesia and euphoria. As a result, they display addiction-forming liability that is akin to that of morphine itself.

In contrast, narcotics, while often used interchangeably with opiates in some contexts, is a broader term that refers to a variety of substances that can induce sedation and relieve pain. This includes both legal medications as well as illicit drugs, encompassing more than just those derived from opium.

Cannabinoids are compounds found in cannabis and function differently in the body; they interact primarily with cannabinoid receptors rather than the opioid receptors that opiates affect, leading to a different set of effects and potential for addiction.

Heroin, although it is indeed addictive and is derived from morphine, does not fit the definition