1. cause bread to rise and grow lighter
1. Yeast is used to leaven bread.
2. enliven; make lively, interesting
2. He can always be counted on to leaven a dull conversation.
levare (to raise) (Latin)
when you LEAVE anything in oVEN it will puff up and grow lighter (its bit vague) Think of Balloon: LEAVE aNd it will go up, therefore cause to rise or grow lighter Lift up to the hEAVEN. tht is rise u ll rise up to heaven only when u grow lighter (in wt. )