- Androecium
- Andrology
- Angst
- Angular
- Angular diameter
- Aniconism
- Animal kingdom
- Animistic
- Anise seed
- Anise seed herb
- Annexe
- Another
- Anothers wife
- Ansi
- Antagonize
- Antarctic
- Ante
- Anvil
- Anxiously
- Any eye-salve
- Any more
- Anybody
- Anyone
- Anything real
- Anytime
- Aortal
- Apart from
- Ape
- Aperitif
- Appal
- Appall
- Appallingly
- Apparent
- Apparition
- Appear
- Appellate
- Appendage
- Appendix
- Apperception
- Appetising
- Appetitive
- Appetizing
- Apple
- Applet
- Appleton layer
- Aptitude
- Aptness
- Aqua
- Aquamarine
- Aquaphobia
- Aquarius
- Aquatic
- Aqueous
- Aquifer
- Arabia
- Arabic
- Arak
- Arbitrary
- Arbor
- Arcot
- Arcturus
- Are
- Area code
- Arena
- Areola
- Argania
- Argon
- Armoury
- Armpit hair
- Arms race
- Army
- Arouses
- Arrack
- Arras
- Array
- Arraying
- Arrear
- Arrive
- Arrogance
- 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