- 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
- At work
- At-the-outset
- Ataraxy
- Ataxia
- Athenaeum
- Athletic
- Atmospheric air
- Atomic power
- Atomizer
- Atrium
- Atrocity
- Attache
- Attainability
- Attainable
- Attainment of manhood
- Attempt
- Attentiveness
- Attenuation
- Attested
- Atticism
- Attorney
- Attractive
- Attribution
- Auberge
- Audacious
- Audible
- Audiology
- Audiometer
- Audiovisual
- Auditory
- Augean
- August
- Augustan
- Auld
- Auld lang syne
- Aural
- Aureole
- Auricular
- Aurora australis
- Auspice
- Auspicious
- Auspicious time
- Austerity
- Authenticated
- Author of atharva veda
- Authoratative treatise
- Authoress
- Authorship
- Auto
- Auto score
- Auto-suggestion
- Autocracy
- Autogenously
- Autolysis
- Automatic
- Automatic check
- Adams apple
- Adapt to
- Adaptableness
- Adaptation
- Adc
- Add on
- Add up
- Addicted
- Addictive
- Adding
- Additional
- Addle
- Addled
- Address field
- Addressee
- Adduce
- Adhere
- Adhering
- Adjacent
- Adjoin
- Adjudge
- Adjudication
- Adjudicator
- Adjunct
- Adman
- Administer
- Administrating
- Administration
- Administrative
- Administrative system