LSD

¹ American  

abbreviation

Pharmacology.

1. a crystalline solid, C 20 H 25 N 3 O, the diethyl amide of lysergic acid, a powerful psychedelic drug that produces temporary hallucinations and a schizophrenic psychotic state.

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LSD ² American  

abbreviation

U.S. Navy.

plural

LSDs

1. a seagoing, amphibious ship capable of carrying and launching assault landing craft from a large, inner compartment that can be flooded, and of making emergency repairs at sea to smaller ships.

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LSD ³ American  

abbreviation

1. least significant digit.

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L.S.D. ⁴ American  

Or £.s.d.,

abbreviation

1. pounds, shillings, and pence.

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LSD ¹ British  

noun

1. Informal name (as an illegal hallucinogen): acid.  lysergic acid diethylamide; a crystalline compound prepared from lysergic acid, used in experimental medicine and taken illegally as a hallucinogenic drug

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L.S.D. ² British  

abbreviation

1. librae, solidi, denarii

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LSD Scientific  

/ ĕl′ĕs-dē′ /

1. Short for lysergic acid diethylamide. A crystalline compound that is a synthetic derivative of lysergic acid. It is used as a powerful hallucinogenic drug. Chemical formula: C ₂₀ H ₂₅ N ₃ O.

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LSD Cultural  

1. A drug, lysergic acid diethylamide, that produces hallucinations similar to those of a psychosis. Persons on LSD “trips,” which may last for many hours, undergo distortions of their perceptions of space and time and may lose all contact with reality.

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Etymology

Origin of LSD¹

First recorded in 1945–50; abbreviaion of German Lysergsäure-Diäthylamid “lysergic acid diethylamide”

Origin of LSD²

First recorded in 1940–45; abbreviation of l(anding), s(hip), d(ock)

Origin of L.S.D.⁴

From Latin lībrae “pounds (sterling),” libra ¹ ( def. ), pound ² ( def. ); solidī , solidus ¹ ( def. ); dēnāriī denarius ( def. )

Example Sentences

Croatia's preventive vaccination, after EU approval, meant LSD was never reported in the country, despite outbreaks nearby in Serbia and Montenegro.

From Barron's • Dec. 17, 2025

LSD is a highly contagious bovine disease which is transmitted mainly by fly-bites.

From BBC • Dec. 12, 2025

In the end, Mead appears not to have taken LSD.

From Slate • Feb. 10, 2024

Mr. Olson was working at Fort Detrick and was unwittingly drugged with LSD in a CIA mind-control experiment that ended with him falling to his death from a New York hotel window.

From Washington Times • Dec. 6, 2023

Australian officials were working with Indonesia to reassure market participants that all animals exported from Australia complied with Indonesian requirements, including being free of LSD, Agriculture Minister Murray Watt said in a statement on Sunday.

From Reuters • Jul. 31, 2023