1
[ noun ] the quality of being similar

Used in print

(Irving Stone, The Agony and the Ecstasy....)

Next he turned_to wax because there was a similarity of wax to marble in tactile quality and translucence .

2
[ noun ] a Getalt principle of organization holding that (other things being equal) parts of a stimulus field that are similar to each other tend to be perceived as belonging together as a unit
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