- 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
- 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
- Abetter
- Abeyance
- Abhishekam
- Abhorrent
- Ability
- Abiogenisis
- Abjection
- Ablactation
- Ableism
- Abnegation
- Above-mentioned
- Abrakadabra
- Abruptly
- Abscessed
- Abscond from
- Absconder
- Absent-mindedness
- Abstruse
- Absurbed notion
- Absurdist
- Abulia
- Abundance