lush (adj.)It seems to have been popularised by Gavin & Stacey. Perhaps it was a Welsh word?
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" (from PIE root *sleg- "be slack, be languid"). 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.
lush (n.)
"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.)
produced or growing in extreme abundance;
Synonyms: exuberant / luxuriant / profuse / riotous
lush (adj.)
having strong sexual appeal;
Synonyms: juicy / luscious / red-hot / toothsome / voluptuous
lush (adj.)
ostentatiously rich and superior in quality;
these architecture magazines are full of the lush interiors of the rich and famous
Synonyms: deluxe / gilded / grand / luxurious / opulent / princely / sumptuous
lush (adj.)
tender and full of juice;
lush fruits
Synonyms: succulent
2
lush (n.)
a person who drinks alcohol to excess habitually.
HTH 🤔