From Longman Dictionary of Contemporary Englishdottydot‧ty /ˈdɒti $ ˈdɑːti/ adjective old-fashioned informal 1 CRAZYslightly crazy2 → dotty about somebody/something
Examples from the Corpus
dotty• Not that he was dotty all the time.• This enchantingly dotty building has recently been restored and is now on the market.• Some of these are dotty by anyone's standards.• a dotty old lady• Any attempt to increase tolerance - however dotty or blush-making - should be respected.• I should go quite dotty without work, and there is none for me in Venice now.Origin dotty (1800-1900) Scottish English dottle “stupid person”, from dote “to be stupid” ((12-19 centuries)) 