Here are a few more words to help you beautify your language and make it more impressive.

loud enough to be heard clearly- Audible
Kindly be louder, you are not audible at the back.

something fit to be eaten- Edible
The food served in our canteen is just not edible; it is never cooked properly.

someone who enjoys talking only about himself- Egotist
I don’t enjoy his egotist talks.

filled with excessive enthusiasm for anything being done- Fanatic
We know our presentation is the best but you better calm down and stop behaving like a fanatic.

something that can’t be changed or altered- Immutable
The clauses laid down in the contract are immutable.