Question: words that are uncommonly used?
Answer: abide - put up with, tolerate; await;
abjure - renounce, turn away from.
abroad - in the open, at large.
adamant - diamond, or (more generally) any very hard substance.
afield - away, especially from home.
aforetime - in earlier times.
aghast - terrified, amazed.
agin - a dialect word meaning "against", "next to"