Definition of wantage in US English:

wantage

noun

US
rare
  • The amount of something lost during transportation; (hence) the amount by which a barrel or other container falls short of being full.

Origin

Mid 18th century; earliest use found in Gerard G. Beekman (1719–1797). From want + -age.

Pronunciation

wantage

/ˈwɒntɪdʒ/