domaren looks/sounds like domoren in dutch. Which means silly/dumb person (usually jokingly said to a child, so not completely interchangeable with idiot)
A fun way to remember it, since this so far is one of the few words (also läkaren) I don't recognise as a similar word in the languages I know.
(ps before pressing post, I looked up the etymology, I see now that doom is related, dom means doom or judgement. Guess I have found another way to remember it :) )
(pps apparently for spanish and italian people it shóuld be a recognisable word)