A substance used to produce fermentation in dough or a liquid.

synonym: leavening.

Roget 663: bane, curse; evil etc. 619; hurtfulness etc. (badness) 649^†; painfulness etc. (cause of pain) 830; scourge etc. (punishment) 975; damnosa hereditas [Lat.]; white elephant.    sting, fang, thorn, tang, bramble, brier, nettle.    poison, toxin; teratogen; leaven, virus venom; arsenic; antimony, tartar emetic; strychnine, nicotine; miasma, miasm^†, mephitis^†, malaria, azote^†, sewer gas; pest.    [poisonous substances, examples] Albany hemp^†, arsenious oxide, arsenious acid; bichloride of mercury; carbonic acid, carbonic gas; choke damp, corrosive sublimate, fire damp; hydrocyanic acid, cyanide, Prussic acid, hydrogen cyanide; marsh gas, nux vomica [Lat.], ratsbane^†.    [poisonous plants] hemlock, hellebore, nightshade, belladonna, henbane, aconite; banewort^†, bhang, ganja^†, hashish; Upas tree.    [list of poisonous substances] Toxline (online).    rust, worm, helminth [Med.], moth, moth and rust, fungus, mildew; dry rot; canker, cankerworm; cancer; torpedo; viper etc. (evil doer) 913; demon etc. 980.    [Science of poisons] toxicology.    ... show more

Roget 659: deterioration, debasement; wane, ebb; recession etc. 287; retrogradation etc. 283^†; decrease etc. 36.    degeneracy, degeneration, degenerateness; degradation; depravation, depravement; devolution; depravity etc. 945; demoralization, retrogression; masochism.    impairment, inquination^†, injury, damage, loss, detriment, delaceration^†, outrage, havoc, inroad, ravage, scath^†; perversion, prostitution, vitiation, discoloration, oxidation, pollution, defoedation^†, poisoning, venenation^†, leaven, contamination, canker, corruption, adulteration, alloy.    decline, declension, declination; decadence, decadency^†; falling off etc. v.; caducity^†, decrepitude.    decay, dilapidation, ravages of time, wear and tear; corrosion, erosion; moldiness, rottenness; moth and rust, dry rot, blight, marasmus^†, atrophy, collapse; disorganization; delabrement etc. (destruction). 162; aphid, Aphis, plant louse, puceron^†; vinefretter^†, vinegrub^†.    wreck, mere wreck, honeycomb, magni nominis umbra [Lat.]; jade, plug, rackabones [U.S.], skate [U.S.]; tackey^†, tacky [U.S.].    ... show more

Roget 653: uncleanness etc. adj.; impurity; immundity^†, immundicity^†; impurity etc. 961 [of mind]. defilement, contamination etc. v.; defoedation^†; soilure^†, soiliness^†; abomination; leaven; taint, tainture^†; fetor etc. 401^†.    decay; putrescence, putrefaction; corruption; mold, must, mildew, dry rot, mucor, rubigo^†.    slovenry^†; slovenliness etc. adj.; squalor.    dowdy, drab, slut, malkin^†, slattern, sloven, slammerkin^†, slammock^†, slummock^†, scrub, draggle-tail, mudlark^†, dust-man, sweep; beast.    dirt, filth, soil, slop; dust, cobweb, flue; smoke, soot, smudge, smut, grit, grime, raff^†; sossle^†, sozzle^†.    sordes^†, dregs, grounds, lees; argol^†; sediment, settlement heeltap^†; dross, drossiness^†; mother^†, precipitate, scoriae, ashes, cinders.    recrement^†, slag; scum, froth.    hogwash; ditchwater^†, dishwater, bilgewater^†; rinsings, cheeseparings; sweepings etc. (useless refuse) 645; offscourings^†, outscourings^†; off scum; caput mortuum [Lat.], residuum, sprue, fecula [Lat.], clinker, draff^†; scurf, scurfiness^†; exuviae [Lat.], morphea; fur, furfur^†; dandruff, tartar.    riffraff; vermin, louse, flea, bug, chinch^†.    mud, mire, quagmire, alluvium, silt, sludge, slime, slush, slosh, sposh [U.S.].    spawn, offal, gurry [U.S.]; lientery^†; garbage, carrion; excreta etc. 299; slough, peccant humor, pus, matter, suppuration, lienteria^†; faeces, feces, excrement, ordure, dung, crap [Vulg.], shit [Vulg.]; sewage, sewerage; muck; coprolite; guano, manure, compost.    dunghill, colluvies^†, mixen^†, midden, bog, laystall^†, sink, privy, jakes; toilet, john, head; cess^†, cesspool; sump, sough, cloaca, latrines, drain, sewer, common sewer; Cloacina; dust hole.    sty, pigsty, lair, den, Augean stable^†, sink of corruption; slum, rookery.    ... show more

Roget 320: levity; lightness etc. adj.; imponderability, buoyancy, volatility.    feather, dust, mote, down, thistle, down, flue, cobweb, gossamer, straw, cork, bubble, balloon; float, buoy; ether, air.    leaven, ferment, barm^†, yeast.    lighter-than-air balloon, helium balloon, hydrogen balloon, hot air balloon.    convection, thermal draft, thermal.    ... show more

Roget 153: cause, origin, source, principle, element; occasioner^†, prime mover, primum mobile [Lat.]; vera causa [Lat.]; author etc. (producer) 164; mainspring; agent; leaven; groundwork, foundation etc. (support) 215.    spring, fountain, well, font; fountainhead, spring head, wellhead; fons et origo [Lat.], genesis; descent etc. (paternity) 166; remote cause; influence.    pivot, hinge, turning point, lever, crux, fulcrum; key; proximate cause, causa causans [Lat.]; straw that breaks the camel's back.    ground; reason, reason why; why and wherefore, rationale, occasion, derivation; final cause etc. (intention) 620; les dessous des cartes [Fr.]; undercurrents.    rudiment.    egg, germ, embryo, bud, root, radix radical, etymon, nucleus, seed, stem, stock, stirps, trunk, tap-root, gemmule^†, radicle, semen, sperm.    nest, cradle, nursery, womb, nidus, birthplace, hotbed.    causality, causation; origination; production etc. 161.    ... show more

Roget 56: component; component part, integral part, integrant part^†; element, constituent, ingredient, leaven; part and parcel; contents; appurtenance; feature; member etc. (part) 51; personnel.    ... show more

Dutch: gistmiddel, rijsmiddel

An influence that works subtly to lighten or modify something:
— His sermons benefited from a leavening of humor.

synonym: leavening.

Cause to puff up with a leaven:
— Unleavened bread.

synonyms: prove, raise.

Roget 469: qualify, limit, modify, leaven, give a color to, introduce new conditions, narrow, temper.    waffle, quibble, hem and haw (be uncertain) 475; equivocate (sophistry) 477.    depend, depend on, be contingent on (effect) 154.    allow for, make allowance for; admit exceptions, take into account; modulate.    moderate, temper, season, leaven.    take exception.    ... show more

Roget 320: be light etc. adj.; float, rise, swim, be buoyed up.    render light etc. adj.; lighten, leaven.   

Roget 653: be unclean, become unclean etc. adj.; rot, putrefy, ferment, fester, rankle, reek; stink etc. 401; mold, molder; go bad etc. adj.. render unclean etc. adj.; dirt, dirty; daub, blot, blur, smudge, smutch^†, soil, smoke, tarnish, slaver, spot, smear; smirch; begrease^†; dabble, drabble^†, draggle, daggle^†; spatter, slubber; besmear &c., bemire, beslime^†, begrime, befoul; splash, stain, distain^†, maculate, sully, pollute, defile, debase, contaminate, taint, leaven; corrupt etc. (injure) 659; cover with dust etc. n.; drabble in the mud^†; roil.    wallow in the mire; slobber, slabber^†.    ... show more