I've got one that is 12 letters:
Effervescent
Its definition is:
ef·fer·ves·cent/ˌefərˈvesənt/Adjective:Chat with our AI personalities
I've is a word that means I have. I'll is a word that means I will.
Pester is a six letter word that means to annoy
im not sure about a 7 letter word, but i do know i 8 letter word that starts with s and means the right to vote, the word is... sufferage.
Plenty.It is a six-letter word.
A seven letter word that means a high shrill sound would be "whistle".