- Arras
- Array
- Arraying
- Arrear
- Arrive
- Arrogance
- Arrow-tip
- Art of arms
- Art of dancing
- Art paper
- Artefactual
- Artery
- Arthritis
- Artichoke
- Artichokes
- As free as air
- As helpless as a babe
- As i see it
- As it comes
- As it stands
- As keen as mustard
- As large as life
- As many
- As matter of
- As much as possible
- As of
- Ascending
- Ascending node of caput draconis
- Ascii
- Ascription
- Aseity
- Asepsis
- Ash
- Ash wednesday
- Ash-gourd
- Ask for a blank cheque
- Ask for the moon
- Assembling
- Assertion
- Assessment
- Assets
- Assignation
- Assignee
- Assimilation
- Assist in
- Associates
- Association
- Astrogeology
- Astroid
- Astrologers
- Astronaut
- Astrophysicist
- Asvamedha sacrifice
- Asymmetrical
- Asymptote
- At a loose end
- At a price
- At a run
- At a stroke
- At all
- At any cost
- At any moment
- At every turn
- At first light
- At first sight
- At great length
- At least
- At most
- At night
- At odds
- At this rate
- At time
- At war
- Atavism
- Ate
- Atheist
- Atlas
- Atoll
- Atomic energy
- Attendants
- Attended by
- Attendees
- Attender
- Attested milk
- Attire
- Attorneys
- Attract
- Attraction
- Attune
- Aureus
- Auricle
- Auspices
- Autarchy
- Authentically
- Authorative person
- Authorial
- Authorise
- Authoritatively
- Authority
- Authorization