Fully equipped, decorated, or dressed up (usually written as 'decked out' with a space).
From deck (to cover/decorate) + out (thoroughly). This phrasal adjective became popular in American English in the 20th century.
The phrase 'decked out' originally meant 'having a deck added'—like a ship—but evolved to mean 'fully decorated or equipped,' often used for cars, rooms, or fancy outfits!
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