Colderest
Not warm. Extremely cold. More cold than colder.
It was cold out yesterday, but today it's even colder. Tomorrow is supposed the colderest for the week.
colderestic
Not warm. Extremely cold. More cold than colder or colderest.
It was cold out yesterday, but today it's even colder. Tomorrow is supposed to be the colderest for the week. Next week is going to be colderestic!