drug

https://doi.org/10.1351/goldbook.D01863
Any substance which when absorbed into a living organism may modify one or more of its functions. The term is generally accepted for a substance taken for a therapeutic purpose, but is also commonly used for abused substances. Synonymous with medicine, pharmaceutical.
Source:
PAC, 1993, 65, 2003. (Glossary for chemists of terms used in toxicology (IUPAC Recommendations 1993)) on page 2040 [Terms] [Paper]