- Assafoetida
- Assail
- Assam
- Assassinate
- Assault
- Assay
- Assured
- Asthenia
- Astis
- Astonished
- Astraddle
- Astral body
- Astray
- 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
- Avionics
- Awake
- Awe
- Awe-inspiring
- Awestruck
- Awhile
- Awkwardly
- Awn
- Agoraphobic
- Avoirdupois
- Amaranthus
- Antiquary
- Auctor
- A disciple who lodges with his preceptor
- A divine ministrel
- A dogs life
- A dry
- A false alarm
- A fiche
- A fish
- A floating voter
- A form of verse in which each line contains eight letters
- A golden parachute
- A good innings
- A good thing
- A grain of paddy
- A hollow laugh
- A host in himself
- A jam session
- A kings ransom
- A lack all
- A laughing stock
- A lazy susan
- A little water
- 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 plant with sweet-scented roots
- A plum job
- A pretty kettle of fish