- Aorta
- Ap
- Apace
- Apart
- Apartheid
- Apartment
- Apeman
- Aphasia
- Aphnology
- Aphonia
- Aphtha
- Apiarist
- Apiary
- Apiece
- Apl
- Apologize
- Apophthegm
- Apoplexy
- Apostolic
- Apothecary
- Applicant
- Application software
- Applied
- Applique
- Apply
- Appoint
- Appointment
- Appologised
- Appoointed
- Apportioning
- Apportionment
- Appose
- Appraisable
- Appraisee
- Appreciably
- Appreciate
- Aptly
- Aqua regia
- Aquaculture
- Arab
- Arabian jasmine
- Arbiter
- Arbitral
- Arboreal
- Arcade
- Arch-enemy
- Archaeologically
- Archaically
- Archangel
- Archduke
- Arched
- Archers
- Archetype
- Archie
- Arching
- Architect of gods
- Arid
- Arise
- Arisen
- Aristocracy
- Arithmetic
- Arithmetic progression
- Arithmetical progression
- Armada
- Armadillo
- 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