- Approach
- Approached
- Approbation
- April fool
- Arboreal
- Arcade
- Arch-enemy
- Archaeologically
- Archaically
- Archangel
- Archduke
- Arched
- Archers
- Archetype
- Archie
- Arching
- Architect of gods
- 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
- Askew
- Asocial
- Asp
- Asparagus
- Aspect
- Asperity
- Aspersions
- Asphodel
- Asphyxiate
- Assamese
- Assassination
- Assaulting
- Astro
- Astrobotany
- Astrolabe
- Astrological
- Astrology
- Astronomer
- Astronomical
- Astrophysics
- Asunder
- Aswamedha
- Asylum
- Asymmetry
- At a snails pace
- At peace
- At rest
- At school
- At the drop of a hat
- At the end of the tether
- At the full
- At the sea
- At the wicket
- Atomizer
- Atrium
- Atrocity
- Attache
- Attainability
- Attainable
- Attainment of manhood
- Attempt
- Aural
- Aureole
- Auricular
- Aurora australis
- Auspice
- Auspicious
- Auspicious time
- Austerity
- Authenticated