- Antipathy
- Antipodes
- Antipole
- Antiquated
- Antitoxin
- Antler
- Antonym
- Ants hill
- 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
- Appreciative
- Apprentice
- Apprenticeship
- Apprised
- Approach
- Approached
- Approbation
- April fool
- Architrave
- Archivolt
- Archon
- Ardor
- Ardour
- Argentine
- Argosy
- Arguable
- Argue
- Argus
- Aromatherapy
- Arose
- Arouse
- Aroused
- Arpanet
- Arraign
- Arrangement
- Arrayed
- Arrestable
- Articleship
- Artifice
- Artificial
- Artificial intelligence
- As opposed to
- Artificial satellite
- Artillery
- Artisan
- Artisans
- Arty
- Arum
- Aruna
- As a matter of fact
- As a rule
- As one likes
- As per
- As plain as the nose
- As pleased as punch
- As sharp as a needle
- As sure as gun
- As ugly as in
- As ugly as sin
- Asafoetida
- Ascend
- Ascended
- Ascent
- Ascertain
- Ascetic
- Ascites
- Ascorbic acid
- Asepticism
- Ash melon
- Ash-coloured
- Ash-pit
- Ashamed
- Ashtray
- Asinine