- acroter
- acroterion
- acroterium
- acrotism
- Acrux
- acrylaldehyde
- acrylamide
- acrylate
- acrylic
- acrylic acid
- acrylic ester
- acrylic fiber
- acrylic fibre
- acrylic resin
- acrylonitrile
- acrylyl
- acrylyl group
- act
- ACT
- act.
- acta
- actable
- Actaeon
- actant
- Acta Sanctorum
- act call
- act curtain
- actg
- actg.
- ACTH
- actin
- actin-
- actinal
- acting
- acting area
- actinia
- actinian
- actinic
- actinic ray
- actinide
- actinide series
- actiniform
- actinin
- actinism
- actinium
- actinium series
- actino-
- actinobacillosis
- actinobacillus
- actinobiology
- actinochemistry
- actinodermatitis
- actinodrome
- actinogram
- actinograph
- actinoid
- actinolite
- actinology
- actinomere
- actinometer
- actinomorphic
- actinomyces
- actinomycete
- actinomycin
- actinomycosis
- actinon
- actinopod
- actinopterygian
- actinotherapy
- actinouranium
- actinozoan
- action
- ACTION
- actionable
- action at a distance
- actioner
- action figure
- action grant
- action line
- action painting
- action potential
- action replay
- action reporter
- actions speak louder than words
- Actions speak louder than words
- action stations
- action verb
- Actis
- Actium
- activate
- activated alumina
- activated carbon
- activated charcoal
- activated mine
- activated sludge
- activation analysis
- activation energy
- activator
- active
- active centre
- active duty
- active galactic nucleus
- active galaxy
- active immunity
- active layer
- active list
- actively
- active margin
- active mass
- active matrix
- active-matrix
- active optics
- active reason
- active safety
- active service
- active shooter
- active site
- active sun
- active transport
- active vocabulary
- active voice
- activewear
- activin
- activism
- activist
- activities
- activity
- activity of daily living
- activize
- acto
- act of contrition
- act of faith
- act of God
- Act of Toleration
- Act of Uniformity
- act of war
- actomyosin
- acton
- Acton
- act on
- act one's age
- actor
- Actor
- actorish
- actor-manager
- actor-proof
- Actors' Equity Association
- act out
- ACTP
- ACTRA
- actress
- actressy
- Acts of the Apostles
- ACTT
- ACTU
- actual
- actual bodily harm
- actual cost
- actualism
- actualité
- actuality
- actualization
- actualize
- actually
- actuals
- actual sin
- actuarial
- actuary
- actuate
- actuation
- actuator
- act up
- act upon
- actus reus
- act warning
- acuate
- Acuff
- acuity
- aculeate
- aculeus
- acultural
- acumen
- acuminate
- acupoint
- acupressure
- acupuncture
- acupuncturist
- acus
- acusector
- acutance
- acute
- acute accent
- acute angle
- acute arch
- acute-care
- acute disease
- acute dose
- acutely
- acute necrotizing gingivitis
- acuteness
- acute respiratory distress syndrome
- acute stress disorder
- acutilingual
- ACV
- ACW
- acyclic
- acyclovir
- acyl
- acyl anhydride
- acylate
- acylation
- acyl group
- acyl halide
- acyloin
- acˈcipitrine
- acˈquittal
- ad
- AD
- ad-
- ad.
- Ada
- ADA
- ad absurdum
- adactylous
- Adad
- ADAD
- adage
- adagio
- Adah
- Adak
- Adam
- Adam's ale
- Adam's apple
- Adam's Bridge
- Adam's cup
- Adam's-needle
- Adama
- Adam and Eve
- Adam-and-Eve
- adamant
- adamantane
- adamantine
- adamantly
- Adamawa
- Adamawa-Eastern
- Adamawa Massif
- Adam Bede
- Adam de la Halle
- ADAMHA
- Adami
- Adamic
- Adamite
- Adamkus
- Adamov
- Adams
- Adams, Ansel
- Adams, John
- Adams, John Quincy
- Adams, Samuel
- adamsite
- Adams-Stokes syndrome
- Adana
- Adapazari
- adapt
- adaptability
- adaptable
- adaptation
- adapter
- adaption
- adaptive
- adaptive optics
- adaptive radiation
- adaptogen
- adaptogenic
- adaptor
- Adar
- ad arbitrium
- Adar I
- Adar II
- Adar Rishon
- Adar Sheni
- ad astra per aspera
- adat
- A date which will live in infamy
- adaxial
- adazzle
- ad break
- ADC
- ad captandum vulgus
- Adcock antenna
- add
- ADD
- ad damnum
- Addams
- Addams, Jane
- addax
- added entry
- added sixth
- added title page
- addend
