The Collaborative International Dictionary of English v.0.48:
Austereness \Aus*tere"ness\, n. 1. Harshness or astringent sourness to the taste; acerbity. --Johnson. [1913 Webster] 2. Severity; strictness; austerity. --Shak. [1913 Webster]WordNet (r) 3.0 (2006):
austereness n 1: extreme plainness [syn: austereness, severity, severeness]