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• LSD
  LSD

  abbreviation

  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.
• L.S.D.
  L.S.D.

  abbreviation

  pounds, shillings, and pence.

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.

LSDs plural

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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L.S.D. ¹ British  

abbreviation

1. librae, solidi, denarii

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LSD ² 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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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),” see libra ¹ ( def. ), pound ² ( def. ); solidī , see solidus ¹ ( def. ); dēnāriī see 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

LSD, which causes blisters and reduces milk production, is a highly infectious viral disease affecting cattle and buffalo that is transmitted by insect biting but which does not pose a risk to humans.

From Reuters • Jul. 31, 2023