1. (someone deranged and possibly dangerous)
crazy, loony, looney, nutcase, weirdo
synonim: nienormalny
synonim: obłąkaniec
synonim: pomyleniec
synonim: pomylony
synonim: szaleniec
synonim: wariat

2. (a person who is regarded as eccentric or mad)
nutter, wacko, whacko: : synonim: szalona głowa
synonim: wariat
synonim: świr
synonim: czubek
synonim: półwariat