- Armature
- Armchair
- Armed
- Armed neutrality
- Armenius
- Armhole
- Armoire
- Armour
- Armour-plated
- Arrogant person
- Arrogantly
- Arrow-root plant
- Arrowhead
- Arrowroot
- Arsenal
- Arsonist
- Art of war
- Artefact
- Artful
- Article
- As common as much
- As common as muck
- As cool as a cucumber
- As far as
- As far as i know
- As far as one can tell
- As far as one is concerned
- As flat as a pancake
- As for
- As good as new
- As long as
- As many again
- Ascended
- Ascent
- Ascertain
- Ascetic
- Ascites
- Ascorbic acid
- Asepticism
- Ash melon
- Ash-coloured
- Ash-pit
- Ashamed
- Ashtray
- Asinine
- Askew
- Asocial
- Asp
- Asparagus
- Aspect
- Asperity
- Aspersions
- Asphodel
- Asphyxiate
- Assamese
- Assassination
- Assaulting
- Assorted
- Assortment
- Assume
- Assure
- Astaghfirullah
- Asterik
- Asteriods
- Asterisk
- Asterism
- Asteroid
- Asthmatic
- Astigmatism
- Astonishment
- Astound
- Astral
- At a stretch
- At a tender age
- At all events
- At dead of night
- At first
- At loggerheads
- At peace
- At rest
- At school
- At the drop of a hat
- At the end of the tether
- At the full
- At the sea
- At the wicket
- Atomizer
- Atrium
- Atrocity
- Attache
- Attainability
- Attainable
- Attainment of manhood
- Attempt
- Auberge
- Audacious
- Audible
- Audiology
- Audiometer
- Audiovisual