- Archaeology
- Archaic
- Archaism
- Archbishopric
- Archeology
- Archipelago
- Architecter
- Architecture
- Aright
- Aril
- Arithmetically
- Arithmetician
- Arjuna
- Armband
- Armlet
- Armoured
- As and when
- Arrogant
- Arrogate
- Arrow
- Arrow and bow
- Arrow point
- Arrow-root flower
- Arrow-root powder
- Arrow-root-flour
- Art director
- Arthropod
- As clear as mud
- As far as possible
- As fit as a fiddle
- As if
- As memory serves
- As much again
- As old as methuselah
- Askant
- Asked
- Asking
- Aslant
- Asleep
- Aspects
- Aspersion
- 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
- Autopsy
- Autotype
- Autumn
- Avacado
- Avarise
- Aver
- Average
- Avid