- Accrete
- Accrued expenses
- Accusatory
- Accuser
- Accusing
- Accusingly
- Ace player
- Acerbic
- Acetic acid
- Ache
- Acid lemon
- Acidophilus
- Acidulous
- Acknowledge
- Acknowledged
- Acm
- Acne
- Acorn
- Acoustic
- Acquisitiveness
- Acquit
- Acrid
- Acridity
- Acrobatic feat
- Act of peace
- Action meter
- Action-packed
- Activate
- Active server pages
- Active service
- Active voice
- Actively
- Activeness
- Activewear
- Actress
- Actual
- Actualise
- Actually
- Acumen
- Acute pain
- Ad-lib
- Adagio
- Answering
- Antagonist
- Antagonistic
- Antares
- Anteater
- Antebellum
- Antecedence
- Antenna
- Anthelmintic
- Anther lobe
- Anthocephalus indicus
- Anthocyanins
- Anthropocene
- Anthropology
- Anthropomorphism
- Anti
- Anti virus software
- Anti-aircraft
- Anti-grammatical
- Anti-incumbent
- Anti-money laundering
- Antibiotic
- Anticipatory bail
- Anticoagulant
- Antidemocrat
- Antidote
- Antifreeze
- Antigen
- Antiperspirant
- Antiphon
- Antiseptic
- Antisocial
- Ants
- Ants in ones pants
- Antsy
- Anxiety disorders
- Any
- Any day now
- Anyplace
- Anything but
- Anything small
- Anyway
- Aourora
- Apathy
- Apepsy
- Aperture
- Apex
- Aphid
- Aphrodisiac
- Apiology
- Apnoea
- Apocryphal
- Apodyopsis
- Apogee
- Apology
- Apophenia
- Apophysis
- Apoptosis