Yeast and baking powder are types of leaven used to make bread.    From LearnThat.org. 

We are leaven, in heaven. leaven-# a substance used to produce fermentation in dough or a liquid.    From Wordnik.com.  [Propeller Most Popular Stories] Reference

So "leaven" is used of false doctrine (Mt 16: 12: compare Mt 13: 33).    From Wordnik.com.  [Commentary Critical and Explanatory on the Whole Bible] Reference

But whether we call the leaven a good or evil thing makes little difference.    From Wordnik.com.  [Essays in Rebellion] Reference

The disciples did not understand him as referring to their doctrine, because the word leaven was not often used among the.    From Wordnik.com.  [Barnes New Testament Notes] Reference

Paul commands them to cleanse out the old leaven, that is, repent.    From Wordnik.com.  [WordPress.com News] Reference

Lay aside, therefore, the evil, the old, the sour leaven, and be ye changed into the new leaven, which is.    From Wordnik.com.  [ANF01. The Apostolic Fathers with Justin Martyr and Irenaeus] Reference

In a physical sense, leaven, which is a rising agent such as yeast is used to make bread rise up during the baking process.    From Wordnik.com.  [Drupal] Reference

The fecret and divine operations of this kingdom are compared to the fermenting of leaven, which is little noticed until the whole mafs is leavened.    From Wordnik.com.  [Ten sermons on the Millennium; or, The glory of the latter days; and five sermons on what ...] Reference

(spiritually) that very leaven, which is to be put away.    From Wordnik.com.  [NPNF1-12. Saint Chrysostom: Homilies on the Epistles of Paul to the Corinthians] Reference

Barbara will turn out to be the particular kind of leaven the freshies need.    From Wordnik.com.  [Marjorie Dean, College Sophomore] Reference

This is the "leaven" that causes humanity to grow, the light that shines in the world.    From Wordnik.com.  [Archive 2008-06-08] Reference

Crucial in this regard is the role of the lay faithful to act as a "leaven" in society.    From Wordnik.com.  [Archive 2008-04-13] Reference

Where the Gloss is thus; "The 'leaven which is in the lump,' are evil affections, which leavens us in our hearts.".    From Wordnik.com.  [From the Talmud and Hebraica] Reference

Instead of being hit over the head, if you can use humor to kind of leaven it a little bit, I think it works better.    From Wordnik.com.  [CNN Transcript Apr 20, 2003] Reference

Eyolf and John Gabriel Borkman, there remain faint traces of the French leaven which is so strong in the earlier plays.    From Wordnik.com.  [The Master Builder] Reference

And now every day the leaven is working.    From Wordnik.com.  [The Tie That Binds] Reference

Amos 4: 5 calls for "leaven," often interpreted as baking powder.    From Wordnik.com. Reference

You are the leaven which is designed to lighten the heavy mass of the world-mind.    From Wordnik.com.  [A Series of Lessons in Gnani Yoga] Reference

But time and the silent power of the "leaven" of truth does wonders -- sometimes works miracles.    From Wordnik.com.  [Our Brother in Black: His Freedom and His Future] Reference

But now, he says, Schasler has persuaded him that the Ugly is the leaven which is necessary to all the special forms of the Beautiful.    From Wordnik.com.  [Aesthetic as Science of Expression and General Linguistic] Reference

"leaven," which a woman took and, like the salt, hid in three measures of meal, till the whole was leavened (Mt 13: 31-33).    From Wordnik.com.  [Commentary Critical and Explanatory on the Whole Bible] Reference

Know ye not that a little leaven leavens the whole lump?.    From Wordnik.com.  [The New Testament of our Lord and Savior Jesus Christ. The common English version, corrected by the final committee of the American Bible Union.] Reference

But, beware of the leaven of the Pharisees and Sadducees!.    From Wordnik.com.  [The New Testament of our Lord and Savior Jesus Christ. The common English version, corrected by the final committee of the American Bible Union.] Reference

A new leaven has entered our personality to dominate and direct it.    From Wordnik.com.  [The Darrow Enigma] Reference

Both leaven the Snookification of the state with a real sense of place.    From Wordnik.com.  [I Heart NJ] Reference

Karlis, the foolish outsider, attempted to leaven the dispute, but he was ignored.    From Wordnik.com.  [The Cool Aunt] Reference

If thy oblation be from the fryingpan, of flour tempered with oil, and without leaven.    From Wordnik.com.  [The Bible, Douay-Rheims, Complete] Reference

If thy oblation be from the fryingpan, of flour tempered with oil, and without leaven: 2: 6.    From Wordnik.com.  [The Bible, Douay-Rheims, Book 03: Leviticus The Challoner Revision] Reference

His valour is enough to leaven whole armies, he is an army himself worth an army of other men.    From Wordnik.com.  [Microcosmography or, a Piece of the World Discovered; in Essays and Characters] Reference

A political meeting, with two picked speakers to leaven a number of dull and uninteresting harangues.    From Wordnik.com.  [Grey Town An Australian Story] Reference

And he charged them saying: Take heed and beware of the leaven of the Pharisees and of the leaven of Herod.    From Wordnik.com.  [The Bible, Douay-Rheims, Book 48: Mark The Challoner Revision] Reference

Still, I appreciated his efforts to leaven what too often appears to be an overly somber reverence for the game.    From Wordnik.com.  [Gruden in the Booth] Reference

Thou shalt not sacrifice the blood of my victim upon leaven, neither shall the fat of my solemnity remain until the morning.    From Wordnik.com.  [The Bible, Douay-Rheims, Book 02: Exodus The Challoner Revision] Reference

Then they understood that he said not that they should beware of the leaven of bread, but of the doctrine of the Pharisees and.    From Wordnik.com.  [The Bible, Douay-Rheims, Complete] Reference

He did not know how to separate the serious from the unimportant, and he had never added the leaven of humor to the day's duties.    From Wordnik.com.  [Our Nervous Friends — Illustrating the Mastery of Nervousness] Reference

Amongst them were certainly many of the picked men of the earth, whose spirit will leaven the whole of Australasia for all time to come.    From Wordnik.com.  [The Art of Living in Australia ; together with three hundred Australian cookery recipes and accessory kitchen information by Mrs. H. Wicken] Reference