alkaloid

noun

al·​ka·​loid ˈal-kə-ˌlȯid 

: any of numerous usually colorless, complex, and bitter organic bases (such as morphine or caffeine) containing nitrogen and usually oxygen that occur especially in seed plants and are typically physiologically active

alkaloidal

ˌal-kə-ˈlȯi-dᵊl 

adjective

Examples of alkaloid in a Sentence

Recent Examples on the Web

Many scientists believe the drug’s primary neuroactive alkaloid, called arecoline, is only noticeable after chewing betel nuts processed with slaked lime. — Andrew Paul, Popular Science, 10 Sep. 2026

No self-respecting living thing would deliberately sniff, let alone eat, any part of the plant, which also contains highly toxic steroidal alkaloids. — ABC News, 8 Sep. 2026

As the recall notice explains, yohimbine is an alkaloid from the bark of the yohimbe tree, usually used for erectile dysfunction in prescription medications, not over-the-counter supplements. — David J. Neal, Miami Herald, 6 Sep. 2026

History and discovery Buprenorphine is derived from thebaine, an alkaloid that occurs naturally in the opium poppy (Papaver somniferum). — Encyclopedia Britannica, 28 Aug. 2026

Word History

First Known Use

1820, in the meaning defined above

Rhymes for alkaloid

• adenoid
• amoeboid
• amyloid
• aneroid
• arachnoid
• asteroid
• benzenoid
• carcinoid
• celluloid
• coronoid
• humanoid
• mongoloid

Medical Definition

alkaloid

noun

al·​ka·​loid ˈal-kə-ˌlȯid 

: any of numerous usually colorless, complex, and bitter organic bases (as morphine or caffeine) containing nitrogen and usually oxygen that occur especially in seed plants and are typically physiologically active

alkaloidal

ˌal-kə-ˈlȯid-ᵊl 

adjective