1 syllable:
ass, bass, basse, blass, bras, brass, brasse, cas, cass, casse, chass, chasse, class, classe, crass, crasse, das, dass, dcass, dclass, ddass, drass, fahs, fass, fasse, frass, gas, gass, gasse, glas, glass, glasse, grass, grasse, hass, jass, kass, kasse, klas, klass, klasse, kras, krass, kvass, lass, lasse, mass., masse, nass, nasse, pass, plas, plass, plasse, prass, ras, rasse, sas, sass, sasse, shass, strass, strasse, tass, tasse, trass, trasse, vass, wrass, wrasse, yass, yeahs

2 syllables:
a-class, aairpass, admass, age class, airgas, airmass, air gas, alas, alass, alsace, amass, amcas, anlass, art class, audace, bad-ass, badass, band-pass, bandpass, bare-ass, barn grass, bay grass, beargrass, bear grass, beer glass, bell-glass, bell glass, bent-grass, bentgrass, bent grass, besace, big-ass, bindass, black bass, blow gas, bluegrass, bromegrass, broom grass, bumpass, bunchgrass, bunch grass, burgrass, bur grass, by-pass, bypass, camass, cane-grass, chagas, cheatgrass, classpass, cloud grass, coal gas, contrasts, cordgrass, cord grass, couch-grass, couchgrass, couch grass, crabgrass, crab grass, crevasse, crown glass, cut-glass, cut-grass, cutgrass, cut glass, damasse, declass, declasse, deergrass, deer grass, depass, dog grass, donbass, dumb-ass, e-glass, e-zpass, eagrass, ecass, eelgrass, egg-glass, emass, en masse, eyeglass, fat-ass, fatass, fieldglass, field glass, filasse, finglas, first-class, first class, flint glass, flute glass, forecasts, form class, forpass, fourth-class, goat grass, goose-grass, goose grass, groundmass, ground bass, ground glass, hair grass, half-ass, hall pass, hand glass, harass, hard-ass, hardass, hardbass, high-class, high brass, hoofdklasse, i-pass, impasse, ipass, jackass, june grass, keepass, kick-ass, kickass, kiss-ass, knotgrass, kompass, kuzbass, lambastes, landmass, lard-ass, lardass, lastpass, lead glass, life class, lovegrass, love grass, low-class, lowpass, low brass, lyme grass, make pass, marsh gas, means grass, metglas, miass, midgrass, milk glass, molasse, morass, navras, nerve gas, newgrass, nordpass, nutgrass, nut grass, ofgas, outclass, outlasts, outpass, owlglass, piepgras, pier glass, pin grass, plate-glass, plate glass, plume grass, portass, potass, quackgrass, quack grass, quartz glass, quick grass, recas, red brass, reed grass, repass, rhodes grass, ribgrass, ricegrass, rice grass, rock bass, rush-grass, rushgrass, rye-grass, ryegrass, rye grass, sambass, sandglass, sawgrass, screen pass, sea-grass, seabass, seagrass, sea bass, serfass, she-ass, short-grass, shortgrass, shot glass, silkgrass, silk grass, slough grass, smart-ass, smartass, smut grass, snodgrass, soft glass, speargrass, spyglass, stained-glass, stained glass, star grass, stone bass, stormglass, string bass, striped bass, sub-bass, subclass, sunglass, sunpass, surpass, sweet grass, switchgrass, switch grass, sword grass, tall-grass, tallgrass, tape grass, tear gas, third-class, third class, tight-ass, timepass, top-class, town gas, transpass, trespass, tresspass, umass, vanasse, velas, verglas, vorace, watch-glass, watchglass, watch glass, wheat-grass, wheatgrass, wild ass, wineglass, wiregrass, wise-ass, witchgrass, witch grass, wool grass, word class, world-class, worldclass, worldpass, yankass, yardgrass, yard grass

3 syllables:
after-grass, aftergrass, ahnenpass, alpha brass, andre de grasse, arrowgrass, arrow grass, autopass, barley grass, barnyard grass, bearing brass, bierglas, bio-mass, black sea bass, blowing gas, boardingpass, boarding pass, botopass, bottle-grass, bottled gas, bottlegrass, bottle grass, brandy glass, bristlegrass, bristle grass, broom beard grass, burning-glass, cabin class, candlemas, candlemass, candy-ass, carpet grass, cartridge brass, channel bass, china grass, code geass, cotton-grass, cotton grass, curly grass, curtelasse, dallisgrass, demi-tasse, devil grass, double-bass, double bass, drinking glass, efficace, energas, english class, europass, fescue grass, fiberglas, fiberglass, fibreglass, figured bass, finger grass, forward pass, fountain grass, foxtail grass, freshman class, galloglass, gallowglass, gangstagrass, goosegrass, grama grass, hardinggrass, harding grass, hippocras, hoppergrass, hour-glass, hourglass, ideal gas, inert gas, interclass, ipocras, isinglass, itar-tass, jenny-ass, jenny ass, johnsongrass, junior class, kylie masse, laughing gas, lemongrass, liqueur glass, looking-glass, looking glass, lower-class, lower class, madecass, manna grass, mardi gras, mark duplass, martinmas, masterclass, meadow-grass, meadowgrass, meadow grass, metaclass, middle-class, middleclass, middlemas, middle class, montparnasse, motorbass, mountain pass, moviepass, mustard gas, naval brass, noble gas, object glass, old witch grass, opal glass, orange grass, orchard grass, overclass, overpass, pampas grass, pane of glass, panic grass, penny grass, peppergrass, pepper grass, perfect gas, perspicace, physics class, piece of ass, plexiglas, plexiglass, poison gas, prairie grass, psycho-pass, push-to-pass, quatermass, rankin/bass, ravenglass, ribbon grass, ripple-grass, rock sea bass, ruling class, safety glass, salt reed grass, sassafras, sassafrass, scurvy-grass, sea lyme grass, second-class, second class, senior class, sewer gas, shangri-las, sheet of glass, silver grass, social class, sonderclass, sophomore class, sour grass, sparagrass, sparrowgrass, superclass, supergrass, tall oat grass, tarantass, thorough-bass, thorough bass, throne of glass, tourist class, tumble grass, underclass, underpass, untertasse, upper-class, upperclass, upper class, velvet grass, water gas, water glass, weatherglass, weierstrass, whitlow grass, wild oat grass, windmill grass, wire glass, wire grass, wiseass, working-class, working class, xbox game pass, xmass, yellow bass, ypocras

4 syllables:
africa/brass, alkali grass, amerigas, bahama grass, bahia grass, bermuda grass, buffalo grass, canary-grass, canary grass, cereal grass, chemistry class, creeping soft grass, crested wheat grass, domestic ass, ecclesiastes, egyptian grass, evergreen grass, feather reed grass, freshwater bass, giant star grass, immigrant class, itaewon class, joey badass, lateral pass, laughing jackass, levy en masse, major form class, manila grass, natural gas, natural glass, optical glass, pain in the ass, poverty grass, producer gas, ravenna grass, reed meadow grass, scorpion-grass, sergeant first class, shatterproof glass, snake in the grass, soluble glass, spotted black bass, sunday school class, tall meadow grass, timothy-grass, velvet bent grass, venetian glass, volcanic glass, water star grass, weeping love grass

5 syllables:
admiralty brass, african love grass, african wild ass, alligator grass, australian reed grass, biology class, christopher mintz-plasse, common cotton grass, creeping windmill grass, economyclass, genus sassafras, graduating class, hairy finger grass, hungarian grass, japanese lawn grass, kentucky black bass, kentucky bluegrass, korean lawn grass, laminated glass, lower-middle-class, magnifying glass, mercedes-benz c-class, mercedes-benz e-class, mercedes-benz g-class, mercedes-benz s-class, mercedes-benz sl-class, pheasant under glass, reed canary grass, through the looking-glass, upper-lower-class, upper-middle-class, yellow bristle grass

6 syllables:
american star grass, carbon monoxide gas, continuing trespass, coronary bypass, european dune grass, fairway crested wheat grass, japanese carpet grass, korean velvet grass, mercedes-benz a-class, midnight in the switchgrass

7 syllables:
interplanetary gas

8 syllables:
liquefied petroleum gas

1 syllable:
spats, hats, katz, flats, bats, cats, fats, rats, pat's, that's

2 syllables:
and that's