Cage is a four-letter word that starts with c and means cell. Or case! Or the 5 letter word Crypt!
The 6-letter word for getting bigger is "grow."
Charisma
Nobody can tell you exactly. However the word will cease to exist when the Sun expands to become a red giant (at which point the Earth will be inside the Sun). This will happen between 4 and 5 billion years in the future. The Earth has been around for about 3.5 billion years.
Biopsy.
A gigaannum, usual symbol Ga, is a unit of time equal to oneAnother word more narrowly used to mean a billion years is "aeon" (eon).
Centenarian by XL
I've is a word that means I have. I'll is a word that means I will.
Billion
A ten letter word that means equal to is equivalent.
Brave is a five-letter word that means gallant.
The four letter word that means, "I forbid," is veto.veto
Pester is a six letter word that means to annoy
centurian Centenari--. A centurian is an ancient Roman soldier. I'd suggest making it the 11 letter word centenarian.
The two-letter word that means "us" is "we."
A six letter word that also means next to is beside
A six letter word that means argue is bicker.