- Apiary
- Apiece
- Apl
- Apologize
- Apophthegm
- Apoplexy
- Apostolic
- Apothecary
- App
- Appealing
- Appearing
- Appease
- Appeased
- Appendectomy
- Appetence-cy
- Appetizer
- Applause
- Appreciative
- Apprentice
- Apprenticeship
- Apprised
- Approach
- Approached
- Approbation
- April fool
- Arboreal
- Arcade
- Arch-enemy
- Archaeologically
- Archaically
- Archangel
- Archduke
- Arched
- Archers
- Archetype
- Archie
- Arching
- Architect of gods
- Arid
- Arise
- Arisen
- Aristocracy
- Arithmetic
- Arithmetic progression
- Arithmetical progression
- Armada
- Armadillo
- Armature
- Armchair
- Armed
- Armed neutrality
- Armenius
- Armhole
- Armoire
- Armour
- Armour-plated
- Aromatherapy
- Arose
- Arouse
- Aroused
- Arpanet
- Arraign
- Arrangement
- Arrayed
- Arrestable
- Articleship
- Artifice
- Artificial
- Artificial intelligence
- As opposed to
- Artificial satellite
- Artillery
- Artisan
- Artisans
- Arty
- Arum
- Aruna
- As a matter of fact
- As a rule
- As one likes
- As per
- As plain as the nose
- As pleased as punch
- As sharp as a needle
- As sure as gun
- As ugly as in
- As ugly as sin
- Asafoetida
- Ascend
- Ascended
- Ascent
- Ascertain
- Ascetic
- Ascites
- Ascorbic acid
- Asepticism
- Ash melon
- Ash-coloured
- Ash-pit
- Ashamed