Synonyms for Thinness (same or very similar meaning)
WordNet sense 1 (the property of being very narrow or thin):
fineness
WordNet sense 2 (the property of being scanty or scattered; lacking denseness):
spareness, sparseness, sparsity
WordNet sense 3 (relatively small dimension through an object as opposed to its length or width):
slenderness, tenuity
WordNet sense 4 (the property of having little body fat):
leanness
From the ODE community, based on WordNet
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