1. 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. [ l ( anding ) s ( hip ) d ( eck )]
2. Pharm. 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. [ Lysergsäure-Diäthylamid lysergic acid diethylamide]
3. See least significant digit .