E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Wan means thin.
(Anglo-Saxon, wan, “deficient”; our wane, as the “waning moon.”) As wasting of the flesh is generally accompanied with a grey pallor, the idea of leanness has yielded to that of the sickly hue which attends it. (Verb wan-ian, to wane.)
