- acquired immune deficiency syndrome
- acquirement
- acquisition
- acquisitive
- acquisitiveness
- acquit
- acquittal
- acre
- acreage
- acrid
- acrimonious
- acrimoniously
- acrimony
- acrobat
- acrobatic
- acrobatics
- acromegaly
- acronym
- acrophobia
- Acropolis
- across
- across-the-board
- acrostic
- acrylic
- act
- ACT
- acting
- actinic
- actinide
- actinium
- action
- action group
- action movie
- action painting
- action point
- action replay
- action stations
- actionable
- actioner
- action-packed
- activate
- activated
- activation
- active
- active file
- active window
- actively
- activewear
- activism
- activist
- activity
- activity centre
- activity holiday
- actor
- actress
- actressy
- ACTT
- actual
- actuality
- actually
- actuarial
- actuary
- actuate
- acuity
- acumen
- acupressure
- acupuncture
- acupuncturist
- acute
- acute-angled
- acutely
- acuteness
- AD
- ad
- ad hoc
- ad infinitum
- ad interim
- ad nauseam
- ad valorem
- adage
- adagio
- Adam
- adamant
- adamantly
- Adam's ale
- Adam's apple
- adamsite
- adapt
- adaptability
- adaptable
- adaptation
- adapter
- adaptive
- adaptiveness
- ADC
- add
- added
- addend
- addendum
- adder
- adder's tongue
- addict
- addicted
- addiction
- addictive
- add-in
- adding machine
- Addis Ababa
- Addison's disease
- addition
- additional
- additionally
- additive
- addle
- addled
- add-on
- address
- address book
- addressee
- adduce
- adductor
- Adelaide
- Adélie Land
- adenine
- adenoidal
- adenoids
- adenoma
- adenopathy
- adept
- adequacy
- adequate
- adequately
- adhere
- adherence
- adherent
- adhesion
- adhesive
- adhocracy
- adieu
- adipocyte
- adipose
- adjacent
- adjectival
- adjective
- adjoin
- adjoining
- adjourn
- adjournment
- adjt.
- adjudge
- adjudicate
- adjudication
- adjudicator
- adjunct
- adjure
- adjust
- adjustable
- adjusted
- adjustment
- adjutant
- adjutant bird
- adjuvant
- ad-lib
- adman
- admass
- admin
- administer
- administrate
- administration
- administrative
- administrative costs
- administrator
- admirable
- admirably
- admiral
- admiralty
- admiration
- admire
- admirer
- admiring
- admiringly
- admissibility
- admissible
- admission
- admit
- admittance
- admittedly
- admixture
- admonish
- admonition
- adnominal
- ado
- adobe
- adolescence
- adolescent
- Adonis
- adopt
- adopted
- adoption
- adoptive