Covered with snow; past tense of snow; figuratively, deceived or tricked.
From Old English 'snaw' and Germanic roots, the word has meant both the precipitation and the action of falling snow. The figurative sense developed from the imagery of being 'covered' or 'buried' in something.
To be 'snowed' into thinking something means you've been covered by layers of deception, much like snow buries the ground—it's a metaphor that works because snow literally obscures what's underneath.
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