Worthy of disapproval; able to be disapproved of.
From 'disapprove' + '-able' (adjective suffix meaning 'worthy of' or 'capable of being'). This creates an adjective describing something that merits disapproval.
This word is so rare that most dictionaries don't list it—we just say 'disapprovable behavior' as 'behavior that deserves disapproval'! It shows how '-able' can technically attach to almost any verb, but common sense prevents us from actually using these constructions.
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