Proper words include: book, boom, boon, boor, boot; cook, cool, coop, coot; doom, door; food, fool, foot; good, goon; hood, hook, hoop, hoot; look, loom, loop, loot; mood, moon, moot; noon; pool, poop, poor; rood, roof, rook, room, root; soon, soot; took, tool, toot; wood, woof, wool. There are also some informal or slang words, like boob, coon and toon.
Some six letter words with FF in the middle are:wafflebafflebufferduffermufflepifflesufferduffelpuffindiffer
addassallillofferrbeeseefeepeeteeweezooboocoogoomootoooddebb
Jeep
bookboombootcookcoolcoopcootdoorgoodgoongoophoodhookhooplookloonloomlooplootmoodmoonmoornookpoofpoorpoolrootrookroofroomsoonsoottoottooktoolwoodwoolwoofzoom
Some six letter words that end in double letters:accessacrossapogeebamboobefallboo booboohoobungeebypasscaresscoffeecouleecuckoodecreedegreeduressegressembossenrollentreeexcessgoateeharassHawaiilayofflycheemorassmuumuupayoffpeeweepizazzrebuffrecallrecessrefillremissripoffrunoffscrollscruffsetteeshrillsoireesquallstressstrolltarifftattoothrilltoffeetoupeeunlessvoodoo
Some six letter words with FF in the middle are:wafflebafflebufferduffermufflepifflesufferduffelpuffindiffer
Words that have "tt" in the middle include "butter," "letter," "batter," and "latter." These words typically contain the double "t" between two other letters, contributing to their pronunciation and meaning.
addassallillofferrbeeseefeepeeteeweezooboocoogoomootoooddebb
Some six letter words with OOS in the middle:IgloosKazoosWazoosYahoos
buffcuffmuffpuffballbellbillbullcallcellmallmillmullnullpillpullrollsillselltilltelltallwallwellwillbassbosscussfusshisskisslessmessmissmassmosslosspasssasstossmuttmittbuttdollfallfellfillfull
Eel
Some words that have the letters ME twice in the middle are:amendmentcommencementdismembermentmeantimemeasurementmementomerrimentmesmerisemetronomesometimesummertime
Ill and inn.
sully, sunny
Jeep
bookboombootcookcoolcoopcootdoorgoodgoongoophoodhookhooplookloonloomlooplootmoodmoonmoornookpoofpoorpoolrootrookroofroomsoonsoottoottooktoolwoodwoolwoofzoom
Some six letter words that end in double letters:accessacrossapogeebamboobefallboo booboohoobungeebypasscaresscoffeecouleecuckoodecreedegreeduressegressembossenrollentreeexcessgoateeharassHawaiilayofflycheemorassmuumuupayoffpeeweepizazzrebuffrecallrecessrefillremissripoffrunoffscrollscruffsetteeshrillsoireesquallstressstrolltarifftattoothrilltoffeetoupeeunlessvoodoo