The Collaborative International Dictionary of English v.0.48:
Rancidity \Ran*cid"i*ty\ (r[a^]n*s[i^]d"[i^]*t[y^]), n. [Cf. F. rancidit['e].] The quality or state of being rancid; a rancid scent or flavor, as of old oil. --Ure. [1913 Webster]WordNet (r) 3.0 (2006):
rancidity n 1: the state of being rancid; having a rancid scent or flavor (as of old cooking oil)