Ambiguous
Amendment
Mend
Amino acid
An array of
Anachronism
Analogue
Analogy
Ancestral
Ancestry
Ancestor
Anecdote
Animosity
Antagonism
Antedate
Antedate your letter
Postdate
Anthology
Chrysanthemums
Antibody
Antigen
Antiquity == ancient time
Antique
Apparatus