Pre-
preview
look ahead of time
I will preview the movie before I see it
antecessor
a relative that lived many generations ago
My great-great grandfather is my antecessor.
Antivaxxer
Against vaccination; She was antivaxxer and would not get a Covid shot.
Atypical
not typical, uncommon
It was atypical weather last June when it snowed.
prehistoric
before written history, or before human beings
The woolly mammoth was a prehistoric animal.
anteroom
a small entryway room, or waiting room at a doctor's office
Please leave your coat and shoes in the anteroom before you come in to my house.
antidepressant
a drug that counteracts depression
Some people take antidepressants to cheer themselves up when they are chronically sad.