thrusts
Apple.
immediate
voice, vowel, vocal
stretch
When the first letter of the next word starts with a vowel or the letter H. But of course there are exceptions.... a humble opinion.
A seven letter word that starts with D and ends with T: decrypt
Use "a" before a word that starts with a consonant sound, and use "an" before a word that starts with a vowel sound. For example, "a cat" (pronounced as kæt) and "an apple" (pronounced as əˈpl̩). Remember that it is based on the sound, not the actual letter.
Stretch is a 7 letter word with e as the only vowel. Twelfth is another 7 letter words containing only one vowel.
abreastabstainabridgeacclaimacrobataddressadmiredadornedadoringaerobicafflictalignedallowedamassedamendedamateurangelicanswersappealsappliedapprisearguingarousedarrangeartworkashtrayassumedattractaverageaviatoravoiding
Duchess is a seven letter word.
Garbage
The word "strength" has seven letters and only one vowel.