- ullage (n.) "amount by which a cask or bottle falls short of being full," late 15c., from Anglo-Fr. ulliage (early 14c.), Anglo-L. oliagium (late 13c.), O.Fr. ouillage, from ouiller "to fill up (a barrel) to the bung," lit. "to fill to the eye," from ueil "eye," from L. oculus (see EYE (Cf. eye) (n.)).
Etymology dictionary. 2014.