verb (used with object), verb (used without object) 1.to make or become thick or thicker.
2.to make or grow more intense, profound, intricate, or complex: The plot thickens.
Origin: 1375–1425; late Middle English thiknen <
Old Norse thykkna. See
thick,
-en1 Related forms re·thick·en, verb
un·thick·en, verb (used with object)