Good question - I could only come up with two words that have 6 vowels: facetiously, abstemiously; these words have 7 vowels: adventitiously, and sacrilegiously.
offhand
stretch, scratch, strength...
Groping, chiding, lingers
receive!
immediate
bananas
Sequoia.
sequoia
Stretch is a 7 letter word with e as the only vowel. Twelfth is another 7 letter words containing only one vowel.
Rhythm The 7-letter word is Rhythms
Rhythms.
oatmeal
Oatmeal?
rainbow
Some people maintain that's "rhythms." I don't agree.
The word "sunrise" has the long I as in kite.
The only 7-letter synonym for peace (the answer to this question) may be harmony. But it does not represent an actual period of time as peace does.
One such word is elastic.
someone
3/7