leav ‧ en 1 /ˈlev ə n/ BrE AmE ( also leav‧en‧ing /ˈlev ə nɪŋ/) noun
[ Date: 1300-1400 ; Language: Old French ; Origin: levain , from Vulgar Latin levamen , from Latin levare 'to raise' ]
1 . [uncountable] technical a substance, especially ↑ yeast , that is added to a mixture of flour and water so that it will swell and can be baked into bread ⇨ unleavened
2 . [singular, uncountable] literary something that makes an event or situation less boring, serious, or sad