Longman Dictionary of Contemporary English
Wiktionary
n. (context idiomatic English) A drug deemed to be illegal by a government except for very limited professional testing purposes.
WordNet
n. a drug or chemical substance whose possession and use are controlled by law
Wikipedia
A controlled substance is generally a drug or chemical whose manufacture, possession, or use is regulated by a government, such as illicitly used drugs or prescription medications that are designated a Controlled Drug.
In the U.S., the DEA is responsible for suppressing illegal drug use and distribution by enforcing the Controlled Substances Act. Some precursor chemicals used for the production of illegal drugs are also controlled substances in many countries, even though they may lack the pharmacological effects of the drugs themselves. Substances are classified according to schedules and consist primarily of potentially psychoactive substances. The controlled substances do not include many prescription items such as antibiotics.
Some states in the U.S. have statutes against health care providers self-prescribing and/or administering substances listed in the Controlled Substance Act schedules. This does not forbid licensed providers from self-prescribing medications not on the schedules.
Usage examples of "controlled substance".
From his first formal speech in Indianapolis, soon after his traumatic accession to the Presidency, he'd realized just how strong a narcotic that sort of adulation was, and sure enough, his continued exposure to it had given him the same sort of rush that a controlled substance might.
Cruz enters negotiated plea of pass, of controlled substance in exchange for two-year max.
Or possession of a controlled substance with intent to distribute?
Intoxication without consent, cultivation of a controlled substance, administration of an unknown drug without prior approval, assault by pharmaceutical, and attempted rape.
Since it's a Galtech controlled substance, it can only be released to a qualified Fleet officer.