USA, 1901—wonderfully stylish, elegant or fashionable—a blend of ‘swell’ and ‘elegant’—popularised by its use in the song Well, Did You Evah!, interpreted by Bing Crosby and Frank Sinatra in the 1956 film High Society
USA, 1999—unfashionable or socially awkward in a way regarded as appealing or endearing—blend of ‘adorable’ and ‘dork’—the noun ‘dork’ denotes an odd, socially awkward, unstylish person
UK—2008 ‘fatberg’, after ‘iceberg’: a large mass of fat and waste material in a sewerage system—originally a large lump of congealed cooking fat washed up on a beach—2019 ‘concreteberg’, after ‘fatberg’: a large mass of concrete in a sewerage system, consisting of cement that has been poured down a drain
UK, 1849—transformation into a pumpkin; extravagant or absurdly uncritical glorification—coined after Hellenistic Greek ‘ἀποκολοκύντωσις’, the title of a travesty ascribed to Seneca, according to which the deceased Roman emperor Claudius, instead of being elevated to divine status, is changed into a pumpkin
USA, 1992—to reduce staff numbers to levels so low that work can no longer be carried out effectively—portmanteau, coined by the Trends Research Institute, combining the adjective ‘dumb’, meaning ‘stupid’, and the verb ‘downsize’
USA, 1983—an acronym deliberately formed from a phrase whose initial letters spell out a particular word or words, either to enhance memorability or as a fanciful explanation of a word’s origin—blend of the adjective ‘back’ and of the noun ‘acronym’
USA, early 1980s—depreciative—suggests values epitomised by the McDonald’s restaurant chain, such as low quality, blandness, standardisation, superficiality