leaven / levin are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
leaven: (noun) a substance used to produce fermentation in dough or a liquid. (noun) an influence that works subtly to lighten or modify something.
levin: NA
leaven: l·EH·v·ah·n
levin: l·EH·v·ih·n
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)