Impossible to imagine or picture in your mind; beyond what you can think of or believe.
From Latin 'un-' (not) plus 'imaginable' (able to be imagined), from 'imagine' (to form an image) via Old French from Latin 'imaginari.' A straightforward negation of something that is already imaginable.
The word 'unimaginable' is actually contradictory—if you're calling something unimaginable, you've kind of already imagined it enough to describe it! It's a useful but logically fascinating word that shows how humans stretch language to express the limits of thought.
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