- arcuation
- arcus
- arcus senilis
- arc welding
- ardeb
- Ardebil
- Ardèche
- ardeid
- Ardella
- Arden
- Ardennes
- ardent
- ardently
- ardent spirits
- Ardi
- Ardipithecus
- Ardipithecus kadabba
- Ardipithecus ramidus
- Ardmore
- ardor
- ardour
- Ards
- ARDS
- arduous
- are
- area
- Area 51
- area bombing
- area code
- areal
- areal velocity
- Area of Outstanding Natural Beauty
- area opaca
- area pellucida
- area rug
- area study
- area vasculosa
- area vitellina
- areaway
- areca
- Arecibo
- Arecibo Observatory
- arecoline
- areg
- areligious
- aren't
- arena
- arenaceous
- Arena Chapel
- arena theater
- arena theatre
- arenavirus
- Arendt
- arene
- arenicolous
- arenite
- arenose
- Arensky
- areo-
- areocentric
- areography
- areola
- areole
- areology
- Areopagite
- Areopagus
- arepa
- Arequipa
- Ares
- arete
- arête
- arethusa
- Arethusa
- Aretino
- Arezzo
- arf
- arfvedsonite
- Arg
- Arg.
- argal
- argali
- Argall
- argan
- Argand burner
- Argand diagram
- Argand lamp
- argan oil
- argasid
- Argelander
- argent
- argent-
- argental
- argenteous
- Argenteuil
- argentic
- argentiferous
- Argentina
- argentine
- Argentine
- Argentine ant
- Argentinian
- argentite
- argento-
- argentous
- argentum
- Argerich
- argh
- arghool
- Argie
- argie-bargie
- argil
- argillaceous
- argilliferous
- argillite
- arginase
- arginine
- Argive
- argle-bargle
- Argo
- argol
- Argolis
- argon
- Argonaut
- Argonauts
- Argonne
- Argonne Forest
- argonon
- Argos
- argosy
- argot
- Argovie
- arguable
- arguably
- argue
- Argüedas
- argufy
- argument
- argumentation
- argumentative
- argument from design
- argumentum
- argumentum ad hominem
- argumentum ad populum
- Argun
- argus
- Argus
- Argus-eyed
- argus pheasant
- arguta
- argy-bargy
- argyle
- Argyll
- Argyll and Bute
- Argyllshire
- Argyrol
- arhat
- Arhat
- Århus
- arhythmia
- aria
- Aria
- aria da capo
- Ariadne
- Arian
- Ariane
- Arianism
- Arias Sánchez
- Arica
- arid
- aridification
- aridisol
- aridity
- aridity index
- arid zone
- Ariège
- ariel
- Ariel
- Aries
- arietta
- arigato
- aright
- Arikara
- ariki
- aril
- arillate
- arillode
- Arimathea
- Arimidex
- Ariminum
- Arion
- ariose
- arioso
- Ariosto
- Ariovistus
- arise
- arista
- Arista
- Aristaeus
- aristarch
- Aristarchus
- Aristarchus of Samos
- Aristarchus of Samothrace
- aristate
- Aristide
- Aristides
- Aristippus
- aristo
- aristo-
- aristocracy
- aristocrat
- aristocratic
- aristolochiaceous
- Aristophanes
- Aristophanes of Byzantium
- Aristoteles
- Aristotelian
- Aristotelianism
- Aristotelian logic
- aristotle
- Aristotle
- Aristotle's lantern
- Aristotle Contemplating the Bust of Homer
- aristotype
- arith.
- arithmancy
- arithmetic
- arithmetician
- arithmetic mean
- arithmetic progression
- Arius
- Ariz.
- Arizona
- Arjuna
- ark
- Ark
- Ark.
- Arkadelphia
- Arkansan
- Arkansas
- Arkansas City
- Arkansas stone
- Arkansas toothpick
- Arkansawyer
- Arkhangelsk
- Arkie
- arkose
- ark shell
- arkwright
- Arkwright
- arkwright furniture
- ARL
- Arlberg
- Arleen
- Arlen
- Arlene
- Arles
- Arlington
- Arlington Heights
- Arlington National Cemetery
- Arliss
- Arlon
- arm
- Arm
- ARM
- Arm.
- arm's-length
- armada
- Armada
- Armada, Spanish
- Armada chest
- armadillo
- Armageddon
- Armagh
- Armagnac
- Armalite
- armament
- armamentarium
- Armand
- arm and a leg
- Armani
- armarian
- armarium
- armature
- armature reaction
- Armavir
- armband
- arm candy
- armchair
- Armco
- armed
- armed forces
- Armed Forces Day
- armed neutrality
- armed response unit
- armed response vehicle
- armed robbery
- armed to the teeth
- Armen.
- Armenia
- Armenian
