insane
adj. B1 Intermediate US //ˌɪnˈseɪn// UK //ɪnsˈeɪn// in·sane
adj. extremely foolish, crazy, or shocking. You can also use it to describe something that is very impressive or extreme in a good way.
adj. mentally deranged or extremely foolish; in modern informal contexts, it functions as an intensifier for something remarkable or excessive.
The traffic in the city today is absolutely insane.
It would be insane to quit your job before you have found a new one.
The athlete's performance was nothing short of insane, breaking a world record that many experts believed would stand for at least another decade.
From Latin īnsānus (“unsound in mind; mad, insane”), from in- + sānus (“sound, sane”), equivalent to in- + sane.
Usage
Often used as a gradable adjective with intensifiers like 'completely' or 'totally'.