- Aroma
- Aromatic
- Arpeggio
- Arrange
- Arrest
- Arrest attention
- 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
- Assembler
- Assert
- Assesed lands
- Assess
- Assessee
- Asset
- Assignor
- Assimilated
- Assistance
- Assize
- Associate
- Associated
- 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
- Auctioneer
- Audibility
- Audibleness
- Audibly
- Audit
- Audition
- Auditor
- Aught
- Augmented reality
- August-september
- Augustly
- Authorized person
- Autistic
- Auto index
- Auto-ignition
- Autobiography
- Autodidact
- Automation
- Autonomy
- Avionics
- Awake
- Awe
- Awe-inspiring
- Awestruck
- Awhile
- Awkwardly
- Awn
- Adp
- Airily
- A bad pill to swallow
- A bed of roses
- A bird in hand is worth two in the bush
- A bit much
- A blood relative
- A cardinal error
- A dead duck
- A dead luck
- A dear john letter
- A man of few words
- A man of mark
- A matter of fact
- A matter of life and death