The term 'Morphinelike Drug' refers to an OPIATE, a type of drug derived from the opium poppy plant. Opiates are known for their pain-relieving and sedative effects, and are commonly used to treat severe pain. Morphine is one of the most well-known opiates, and many other drugs have been developed that are similar in structure and effect to morphine. These drugs are referred to as morphinelike drugs.