- abaca
- alkalimeter
- a fit of temper
- agrology
- anaemia
- admitting defeat
- addenda
- alyssum
- analectic
- advisory committee
- aileron
- albumin
- aint
- acquired immunodeficiency syndrome
- and how
- aneurysms
- anew
- angiosperms
- anglicize
- anglo
- anglophobe
- ankle joint
- annals
- anno domini
- announce
- anopheles
- another cup of tea
- answer back to
- answer someone back
- answer the door
- antagonism
- antagonize
- ante-room
- anteater
- antedate
- antediluvian
- antelope
- antenatal
- anti-money laundering
- anticipate
- anticoagulant
- antidemocrat
- antithetical
- antral gastritis
- ants in one's pants
- anus
- anxiety
- aphonia
- aphorism
- apiary
- apiology
- apnoea
- apolitical
- appear
- applicant
- application
- application form
- application software
- application window
- applies
- appointed time
- appose
- appraisable
- appraise
- appraised
- appreciator
- approximate
- approximately
- approximation
- appurtenances
- apriorism
- apron
- arbiter
- arbour
- arcane
- arch-work
- archaeology
- archaic
- archbishop
- archbishopric
- archdeacon
- archer
- archetypal
- architectonic
- architectural
- architecture
- archive
- areal flood
- areca
- areola
- argon
- argosy
- argot
- arguably
- argument
- aria
- arid
- aries
- arise
- arithmetic progression