lush (n.) Look up lush at Dictionary.com
"drunkard," 1890, from earlier slang meaning "liquor" (1790, especially in phrase lush ken "alehouse"), of obscure origin; perhaps a humorous use of lush (adj.) or from a word in Romany or Shelta (tinkers' jargon). It also was a verb, "to drink heavily" (1811).
LUSHEY. Drunk. The rolling kiddeys had a spree, and got bloody lushey; the dashing lads went on a party of pleasure, and got very drunk. ["Dictionary of Buckish Slang, University Wit, and Pickpocket Eloquence," London, 1811]
Hence also Lushington humorous generic name for a tippler (1823).
lush (adj.) Look up lush at Dictionary.com
mid-15c., "lax, flaccid, soft, tender" (obsolete or dialectal), from Old French lasche "soft, loose, slack, negligent, cowardly," from laschier "loosen," from Late Latin laxicare "become shaky," related to Latin laxare "loosen," from laxus "loose" (see lax). The main modern sense of the word, with reference to plant life, "luxuriant in growth," is first attested c. 1600, in Shakespeare. Related: Lushly; lushness.