ullage /ˈʌlɪdʒ 
/ ▸ noun [mass noun] the amount by which a container falls short of being full. ▪ loss of liquid, by evaporation or leakage.
– ORIGIN late Middle English: from Anglo-Norman French ulliage, from Old French euillier ‘fill up’, based on Latin oculus ‘eye’ (with reference to a container's bunghole).
EnglishOxford Dictionary of English
