- As old as methuselah
- 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
- 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
- Autopsy
- Autotype
- Autumn
- Avacado
- Avarise
- Aver
- Average
- Avid
- Avidly
- Aviform
- Axle-tree
- Azolla
- Azure
- 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