The term 'Prescription Specification' refers to the instructions given by a doctor or other healthcare professional when prescribing medication. The crossword solution for this term is 'DRUG, ' which is a four-letter word. DRUG is a general term used to describe any substance that can be used to treat an illness, relieve pain, or alter a person's mental state. Prescription drugs are those that require a doctor's prescription in order to be obtained legally.