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U.S. Navy. 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.
Origin of LSD1
l(anding) s(hip) d(eck)


Pharmacology. 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.
From the German word Lysergsäure-Diäthylamid lysergic acid diethylamide


or £.s.d. l.s.d

pounds, shillings, and pence.
From the Latin word librae, solidī, dēnāriī Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for LSD


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


abbreviation (in Britain, esp formerly)
librae, solidi, denarii
Word Origin
Latin: pounds, shillings, pence
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for LSD

"lysergic acid diethylamide," 1950, from German "Lysergsäure-diäthylamid" (abbreviated LSD in a Swiss journal from 1947). See lysergic. L.s.d. as the abbreviation of "pounds, shillings, and pence" is recorded from 1853.


abbreviation of British currency units, from Latin librae, soldi, denarii, Roman equivalent of "pounds, shillings, pence."

Online Etymology Dictionary, © 2010 Douglas Harper
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LSD in Medicine

LSD (ěl'ěs-dē')
Lysergic acid diethylamide; a crystalline compound derived from lysergic acid and used as a powerful hallucinogenic drug. Also called acid, lysergide.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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LSD in Science
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: C20H25N3O.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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LSD in Culture

LSD definition

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.

The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Slang definitions & phrases for LSD



Lysergic acid diethylamide, a hallucinogenic drug; acid: There is no rite of passage, such as smoking pot or tripping with LSD

[1960s+ Narcotics; found as a chemical abbreviation by 1947 in a Swiss journal]

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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