Failing to recognize how good, strong, or capable someone or something really is; judging as less important than it actually is.
From 'under-' (Old English 'under,' below) plus 'estimate' (from Latin 'aestimare,' to value or assess). The prefix 'under-' means beneath or below, creating the sense of valuing something too low.
History is full of people underestimating their enemies—the British underestimated American colonists, generals underestimated the power of tanks in WWI—showing that misjudging others' abilities has real consequences!
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