- 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
- A measure of
- A milk-n-honey drink
- A narrow escape
- A nasty one
- A near death experience
- A needle in a haystack
- A penny for your thoughts
- A pep talk
- 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
- Abaddon
- Abandoned
- Abandoned woman
- Abandonment
- Abased
- Abashed
- Abba
- Abbreviation
- Abbreviator
- Aberrant
- 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