lievito

Yeast, or baking powder. Also see biga.

lievito di birra: brewer's yeast

lievito madre fritto: sourdough gnocco fritto

lievito madre vivo: 'mother yeast' natural live sourdough starter, easy to make at home

lili: old fashioned liquid rye-based yeast, used to make pane grezzo (Tuscany)

impasto the rising of a yeast dough, From the verb, impastare, to mix. (plural impasti)

Also...

Bertolino lievito: baking powder made with vanilla, for desserts

bustina di lievito or lievito istantaneo: baking powder. Bustina is a sachet

bicarbonato di sodio: baking soda