To hesitate or show uncertainty about something, or to move unsteadily back and forth.
From Old English 'wafian' meaning to wave or flutter. The word combines the sense of physical wavering (like a candle flame) with mental uncertainty, a metaphor that developed in Middle English.
Your confidence can 'waver' just like a candle flame—both meanings come from the same root because uncertainty literally makes you shake! This is why so many emotion words describe physical movements.
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