leaven
noun/ˈlevn/
/ˈlevn/
[uncountable]- a substance, especially yeast, that is added to bread before it is cooked to make it rise
- (figurative) A few jokes add leaven to a boring speech.
Word OriginMiddle English: from Old French levain, based on Latin levamen ‘relief’ (literally ‘means of raising’), from levare ‘to lift’.
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