- As safe as houses
- As soon as
- As soon as possible
- As the case may be
- As the crow flies
- As thin as a lath
- As usual
- Asafetida
- Asap
- Ascendancy
- Assemble
- Assent
- Assessment year
- Assessor
- Asseverate
- Asshole
- Assign
- Assignment
- Assist
- Assistant
- Assistant manager
- Assistant teacher
- Astringent
- Astrological scholar
- Astronomy
- Asura
- Aswathi
- Asymptomatic
- Asynchronous transfer mode
- At
- At a blow
- At a glance
- At a loss
- At this time of day
- At times
- At your service
- Atelier
- Atharvaveda
- Athena
- Atherosclerosis
- Athiest
- Athirst
- Athlete
- Athletic exercise
- Athletics
- Athma
- Atmolysis
- Atmospheric pressure
- Attendance
- Attendance register
- Attends
- Attention
- Attention deficit disorder
- Attentively
- Attenuate
- Attest
- Attic
- Attire abode
- Attirement
- Attitude
- Attracted
- Attracting
- Attributable
- Attribute
- Attributes
- Attrition
- Atypical
- Authoritative dicta
- Authorities
- Authorize
- Auto cad
- Autocratic
- Automated
- Automatic log on
- Automatically
- Autonomous
- Autonomus
- Avoid
- Avouch
- Avowal
- Avowedly
- Avulse
- Avuncular
- Awakening
- Award
- Awfully
- Awkward
- Awoke
- Awry
- Axe
- Axillary bud
- Absolutist
- Aero
- A
- A bad patch
- A bed of thorn
- A big name
- A bird in the hand is worth two in the bush
- A bit thick
- A capital offence