Under  A,  for example, the lexicographers provide entries for Adam, Ad feminam, ageism,  Ain't I a Woman  (Sojourner Truth's speech), and amniocentesis .  Z  is limited to three  Zamani Soweto sisters, Zeitgeist (`Spirit of liberty, equality, and sorority'), and Zugassent (a term for male continence as practised by the Oneida utopian community).
The lexicographers offer numerous entries for A, but there are none under Z.