- Arrhythmic
- Arrived
- Articulation
- Artificial respiration
- Artificialness
- Artist
- Artiste
- Artistic
- Artless
- Arts and part
- Arya race
- As one man
- Asian
- As the crows fly
- As though
- As well
- As yet
- As you sow so you reap
- Ascariasis
- Ascendant
- Ascendent
- Asceticism
- Asecrtained
- Asexuality
- Ash-colour
- Ashore
- Ashy
- Asian palm civet
- Aside
- Ask for
- Assembler
- Assert
- Assesed lands
- Assess
- Assessee
- Asset
- Assignor
- Assimilated
- Assistance
- Assize
- Associate
- Associated
- Astrodome
- Astrolobe
- Astrologer
- Astute
- Astuteness
- Aswathi star
- Aswini devas
- At a gun point
- At all costs
- At all times
- At close quarters
- At dawn
- At full pelt
- At full strain
- At hand
- At knife point
- At length
- At will
- Atelophobia
- Atheism
- Atheistic
- Athri
- Athwart
- Atlantic
- Atmosphere
- Atom
- Atomic
- Atomic number
- Attendant
- Attending
- Attentive
- Attestation
- Attractiveness
- Atwitter
- Au courant
- Aunt
- Aureate
- Aurora
- Auster
- Austere
- Auteur
- Authenticate
- Authentication
- Authorised
- Authoritarianism
- Authoritative
- Authorized person
- Autistic
- Auto index
- Auto-ignition
- Autobiography
- Autodidact
- Automation
- Autonomy
- Avionics
- Awake
- Awe
- Awe-inspiring