Not enough in amount, strength, or quality to do what is needed.
From Latin 'insufficiens' meaning 'not sufficient', from 'in-' (not) + 'sufficiens' (sufficient, adequate), from 'sufficere' (to be enough). It entered English in the 15th century.
‘Insufficient’ sounds cold and technical, but it hides a judgment about some invisible line of ‘enough.’ A lot of stress comes from treating that line as fixed, when in reality it can often be moved or renegotiated.
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