Unable to do something, either because you lack the skills, strength, or mental ability, or because you're not allowed to.
From Latin 'incapabilis': 'in-' (not) + 'capabilis' (able). 'Capable' comes from 'capax' meaning 'spacious' or 'able to hold.'
The Latin root 'capax' literally meant 'spacious'—so 'capable' meant 'having space to hold or contain'—then it evolved to mean 'having the capacity to do something.'
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