gallus; gallows
adjective attractive, wonderful; self-confident, quickwitted, brave, ostentatious, nonchalant; also used as an intensifier. A phonetic slurring of 'gallows', suggesting 'fit for the gallows' and thus 'wicked' – a very early example of 'bad' means 'good'. In the US from the 1840s to 1940s
UK, 1789