- Attacker
- Attain
- Attempt the impossible
- 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 stay of some length
- A sweet-meat
- A tight fit
- A variety of aloe-wood
- A vaunt
- A wandering jew
- A web of lies
- A white lie
- A word of honour
- A word used in the opening of a book to denote auspiciousness
- A yoga pose
- A.m.
- Aadb
- Ab
- Abacinate
- Abnormally
- Abode assylum
- Abolishment
- Abolitionism
- Abolitionist
- Abominable snowman
- Abomination
- Aboriginal
- Abreaction
- Abortive
- Abounding in waves
- About-face
- About-turn
- Above
- Above ones head
- Above ones reach
- Absently
- Absolute
- Aqiqah
- Absorb in
- Absorbed
- Absorbent
- Absorbing
- Abstract art
- Abstractedness
- Accent
- Acceptableness
- Access mode
- Accessary
- Accession
- Accessory
- Accessory gland
- Accident
- Accident-prone
- Acclimatized
- Acclivity
- Accomplice
- Accompliser
- Accomplishment
- Accordance
- Accordion
- Accost
- Acquainted jobs
- Acquatic