leaven
UK[ˈlɛv.ən]US[ˈlɛv.ən]
v
to make dough or bread rise and become light by adding a substance such as yeast
n
a substance, especially yeast, that is added to dough to make it rise
n
a quality or influence that makes something less serious, heavy, or unpleasant
Etymology
the word 'leaven' entered english in the late 14th century from old french 'levain', which itself originated from the latin verb 'levare', meaning 'to lift, raise, or make light'. this latin root is connected to the proto-indo-european base legwh-, meaning 'not heavy, having little weight'. the core concept of making something lighter or causing it to rise was preserved through its journey into english, first applying literally to the process of fermentation in baking. over time, the meaning expanded metaphorically to describe any agent or influence that lightens or enlivens a situation, much as yeast lightens dough.
Analysis
the word is a simplex form. it is derived from the latin verb 'levare', meaning 'to raise, to make light', via old french.
Examples
the baker will leaven the dough overnight for the perfect texture.
sourdough bread uses a natural leaven instead of commercial yeast.
her witty remarks served as a leaven in the otherwise tense meeting.