ullage: [15] Ullage denotes the amount of unfilled space in a wine bottle or barrel. It goes back ultimately to Latin oculus ‘eye’ (a distant relative of English eye), in the metaphorical sense ‘bung-hole of a barrel’. As the word passed into Old French as oeil, this meaning followed it, and it formed the basis of a varb ouiller ‘fill up a barrel to the bung-hole’. From this was derived ouillage, which English acquired via Anglo-Norman ulliage as ullage. => eye, ocular[ullage etymology, ullage origin, 英语词源]