- Apperception
- Appetising
- Appetitive
- Appetizing
- Apple
- Applet
- Appleton layer
- Appreciator
- Apprehensive
- Apprenticed
- Appress
- Approaching
- Approching
- Appropriate
- Approval
- Approximately
- Approximation
- Apricot
- Apt
- Arboretum
- Arcane
- Arch-rival
- Archaeologist
- Archbishop
- Archery
- Architecturally
- Arian
- Aries
- Aristocrat
- Aristocratic
- Arithmetical
- Armed guard
- Armed to the teeth
- Armistice
- Articles of association
- Articulated
- Artillary
- Artilleryman
- Artiodactyl
- Artocarpus heterophyllus
- Artocarpus hirstula
- Arundhati star
- As a result of
- As per rule
- As poor as a church mouse
- As silent as a grave
- As well as
- As-much-as-one-can-do
- Asbestos
- Ascc
- Askance
- Asmall box of chunna
- Asoka forest
- Asokatree
- Aspen
- Aspergillum
- Asperse
- Aspirant
- Aspirin
- Assegai
- Astrogeology
- Astroid
- Astrologers
- Astronaut
- Astrophysicist
- Asvamedha sacrifice
- Asymmetrical
- Asymptote
- At a loose end
- At a price
- At a run
- At one leisure
- At one's fingertips
- At ones last gasp
- At ones own pace
- At that
- Atomic theory
- Atomic warfare
- Atomic weight
- Atoms
- Atomy
- Atony
- Atriculate
- Attach
- Attack
- Attacked
- Attained puberty
- Aubade
- Auberage
- Aubergine
- Aubum hair
- Auction
- Auctionary
- Audience
- Audio
- Audio-visual aids
- Auditory ossicles
- Augean stables
- Augmentation
- Augur