The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
A flat-bottomed vessel developed during World War II to land troops and cargo on open beaches and sometimes used as a weapons platform and hospital ship.
Origin: l(anding) s(hip) t(ank).