What does alkaloid mean?
An alkaloid is a naturally occurring organic compound that contains basic nitrogen atoms and typically exerts powerful physiological effects on humans and animals. Most classical alkaloids are derived from plants — examples include morphine from the opium poppy, caffeine from coffee, quinine from cinchona bark, nicotine from tobacco, and strychnine from nux vomica. The word combines the notion of 'alkali-like' (because these compounds react like bases) with the suffix '-oid', meaning resembling. Because many alkaloids are both medicinally valuable and potentially lethal, they occupy a central place in pharmacology: they underpin important medicines such as painkillers, antimalarials, and stimulants, while also accounting for some of the most notorious plant toxins. The term is chiefly used in scientific, medical, and technical writing rather than everyday speech, where speakers more often name the specific substance involved.
nounAny of a class of naturally occurring, mostly nitrogen-containing organic compounds of plant origin that have marked physiological effects on animals and humans. Alkaloids include substances such as morphine, caffeine, nicotine, quinine, and strychnine.
- A nitrogen-containing natural organic compound of plant origin with pronounced pharmacological effects on humans and animals.
- (In broader modern usage) any naturally occurring organic compound containing basic nitrogen, regardless of whether it derives from plants.
"The chemist isolated a new alkaloid from the bark of the cinchona tree."
"Quinine, an alkaloid extracted from cinchona bark, was long the standard treatment for malaria."
"The toxicology report detected traces of a poisonous alkaloid in the victim's bloodstream."
Standard plural; commonly used when discussing groups or classes of such compounds, e.g. 'opium alkaloids'.
"Tobacco leaves contain several distinct alkaloids besides nicotine."
Many of history's deadliest poisons — strychnine, morphine, nicotine — are all alkaloids, yet so is the caffeine in your morning coffee.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of alkaloid
The word 'alkaloid' was formed in the early nineteenth century by combining 'alkal(i)', ultimately derived through Arabic al-qily (the ashes of saltwort plants) from roots relating to calcined plant ash, with the Greek-derived suffix '-oid', meaning 'resembling'. It was coined by chemists to name the newly discovered class of nitrogenous plant bases that behave like alkalis. Related English words sharing this lineage include 'alkali' and 'alkaline'.
Related word forms
How alkaloid is actually used
Alkaloid is primarily a technical term used in chemistry, pharmacology, botany, and medicine; it is uncommon in casual conversation. It is almost always used as a countable noun and frequently appears in scientific and medical writing when discussing plant-derived drugs, poisons, or medicinal compounds.
Easily confused with alkaloid
Alcohol refers to organic compounds containing a hydroxyl group or to intoxicating drinks, whereas alkaloid refers specifically to nitrogen-containing plant compounds with physiological effects.