Lacking strength, ability, or authority to do something; completely unable to act or change a situation.
From 'power' (from Old French 'poeir' meaning 'ability') combined with the suffix '-less' meaning 'without.' Both parts emphasize complete absence.
The suffix '-less' is incredibly productive in English—speakers can instantly understand 'powerless' even if they've never heard it, because they know the pattern of 'without X.'
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