The Collaborative International Dictionary of English v.0.48:
Yellowness \Yel"low*ness\, n. 1. The quality or state of being yellow; as, the yellowness of an orange. [1913 Webster] 2. Jealousy. [Obs.] [1913 Webster] I will possess him with yellowness. --Shak. [1913 Webster]WordNet (r) 3.0 (2006):
yellowness n 1: yellow color or pigment; the chromatic color resembling the hue of sunflowers or ripe lemons [syn: yellow, yellowness]