Let's terminate these silly questions.
termination
Nine letter words that begin and end with the same letter:beachcombdartboarddecimateddecorateddecreaseddefrostedeffectiveeradicateetiquetteexecutivefireproofflagstafffoolproofgatheringgroundhoghairbrushhopscotchhundredthmagnesiummidstreamnarrationnewswomannightgownnutritionrainwaterrecruitersailboatssentencesturbulent
kill
end
finality
B'ahava באהבה.
Apparently the only common word is wheelbase.
A suffix is a letter or group of letters added to the end of a word to change its meaning or create a new word. It is typically added after the root or base word.
Some nine letter words that start and end with the letter E are:economizeeffectiveeffluenceelaborateelectrodeeliminateeloquenceemergenceempathizeemphasizeenduranceentourageenunciateepitomizeequitableeradicateevaporateevocativeexcessiveexfoliateexquisite
5 nine letter words ending in FF:FlagstaffFoodstuffPikestaffPlaintiffWaitstaff
A suffix is used at the end of a word root to change the meaning of the word.
Some six letter words that end in double letters:accessacrossapogeebamboobefallboo booboohoobungeebypasscaresscoffeecouleecuckoodecreedegreeduressegressembossenrollentreeexcessgoateeharassHawaiilayofflycheemorassmuumuupayoffpeeweepizazzrebuffrecallrecessrefillremissripoffrunoffscrollscruffsetteeshrillsoireesquallstressstrolltarifftattoothrilltoffeetoupeeunlessvoodoo