The Collaborative International Dictionary of English v.0.48:
Spareness \Spare"ness\, n. [Cf. AS. spaernis frugality.] The quality or state of being lean or thin; leanness. [1913 Webster]WordNet (r) 3.0 (2006):
spareness n 1: the property of being scanty or scattered; lacking denseness [syn: sparseness, spareness, sparsity, thinness] 2: the property of having little body fat [syn: leanness, thinness, spareness] [ant: avoirdupois, blubber, fat, fatness]