- arc secant
- arc second
- arcsin
- arc sine
- arc spectrum
- arc tan
- arc tangent
- Arctic
- Arctic char
- Arctic Circle
- Arctic daisy
- Arctic fox
- arctic hare
- Arctic Monkeys
- Arctic Ocean
- Arcticologist
- Arcticology
- Arctic Red River
- Arctic seal
- Arctic Stream
- Arctic tern
- arctic willow
- Arctic Zone
- arctiid
- Arctogaea
- Arctogaean
- Arctogea
- arctophile
- Arcturus
- arcuatearcuate synonyms
- arcuation
- arcus
- arcus senilis
- arc welding
- ardeb
- Ardebil
- Ardèche
- ardeid
- Ardella
- Arden
- Ardennes
- ardentardent synonyms
- ardentlyardently synonyms
- ardent spiritsardent spirits synonyms
- Ardi
- Ardipithecus
- Ardipithecus kadabba
- Ardipithecus ramidus
- Ardmore
- ardorardor synonyms
- ardour
- ARDS
- arduousarduous synonyms
- areare synonyms
- areaarea synonyms
- Area 51
- area bombing
- area code
- arealareal synonyms
- areal velocity
- Area of Outstanding Natural Beauty
- area opaca
- area pellucida
- area rugarea rug synonyms
- area study
- area vasculosa
- area vitellina
- areaway
- areca
- Arecibo
- Arecibo Observatory
- arecoline
- areg
- areligious
- arenaarena synonyms
- arenaceousarenaceous synonyms
- Arena Chapel
- arena theater
- arena theatre
- arenavirus
- Arendt
- arene
- arenicolousarenicolous synonyms
- arenite
- arenosearenose synonyms
- Arensky
- aren't
- areo-
- areocentric
- areography
- areolaareola synonyms
- areole
- areology
- Areopagite
- Areopagus
- arepa
- Arequipa
- Ares
- aretearete synonyms
- arethusa
- Aretino
- Arezzo
- arfarf synonyms
- arfvedsonite
- Arg
- argal
- argali
- Argall
- argan
- Argand burner
- Argand diagram
- Argand lamp
- argan oil
- argasid
- Argelander
- argentargent synonyms
- argental
- argenteous
- Argenteuil
- argentic
- argentiferous
- Argentina
- argentine
- Argentine ant
- argentite
- argento-
- argentous
- argentum
- Argerich
- argh
- arghool
- Argie
- argie-bargie
- argilargil synonyms
- argillaceous
- argilliferous
- argillite
- arginase
- arginine
- Argive
- argle-bargle
- Argo
- argol
- Argolis
- argon
- Argonaut
- Argonauts
- Argonne
- Argonne Forest
- argonon
- Argos
- argosyargosy synonyms
- argotargot synonyms
- Argovie
- arguablearguable synonyms
- arguably
- argueargue synonyms
- Argüedas
- argufyargufy synonyms
- argumentargument synonyms
- argumentationargumentation synonyms
- argumentativeargumentative synonyms
- argument from design
- argumentum
- argumentum ad hominem
- Argun
- Argus
- Argus-eyed
- argus pheasant
- arguta
- argy-bargy
- argyle
- Argyll
- Argyll and Bute
- Argyllshire
- Argyrol
- Arhat
- Århus
- arhythmia
- ariaaria synonyms
- aria da capo
- Ariadne
- Arian
- Ariane
- Arianism
- Arias Sánchez
- Arica
- aridarid synonyms
- aridification
- aridisol
- aridityaridity synonyms
- aridity index
- arid zone
- Ariège
- ariel
- Aries
- arietta
- arigato
- aright
- Arikara
- ariki
- arilaril synonyms
- arillate
- arillode
- Arimathaea
- Arimathea
- Arimidex
- Ariminum
- Arion
- arioseariose synonyms
- ariosoarioso synonyms
- Ariosto
- Ariovistus
- arisearise synonyms
- arista
- Aristaeus
- aristarcharistarch synonyms
- Aristarchus
- Aristarchus of Samos
- Aristarchus of Samothrace
- aristatearistate synonyms
- Aristide
- Aristides
- Aristippus
- aristo
- aristocracyaristocracy synonyms
- aristocrataristocrat synonyms
- aristocraticaristocratic synonyms
- aristolochiaceous
- Aristophanes
- Aristophanes of Byzantium
- Aristoteles
- Aristotelian
- Aristotelianism
- Aristotelian logic
- Aristotle
- Aristotle Contemplating the Bust of Homer
- Aristotle's lantern
- aristotype
- arith.
- arithmancy
- arithmeticarithmetic synonyms
- arithmetician
- arithmetic meanarithmetic mean synonyms
- arithmetic progressionarithmetic progression synonyms
- Arius
- Ariz.
- Arizona
- Arjuna
- arkark synonyms
- Arkadelphia
- Arkansan
- Arkansas
- Arkansas City
- Arkansas stone
- Arkansas toothpick
- Arkansawyer
- Arkhangelsk
- Arkie
- arkose
- ark shell
- arkwright
- arkwright furniture
- ARL
- Arlberg
- Arleen
- Arlen
- Arlene
- Arles
- Arlington
- Arlington Heights
- Arlington National Cemetery
- Arliss
- Arlon
- armarm synonyms
- Armada
- Armada chest
- Armada, Spanish
- armadilloarmadillo synonyms
- Armageddon
- Armagh
- Armagnac
- Armalite
- armamentarmament synonyms
- armamentariumarmamentarium synonyms
- Armand
- arm and a legarm and a leg synonyms
- Armani
- armarian
- armarium
- armature
- armature reaction
- Armavir
- armbandarmband synonyms
- arm candy
- armchairarmchair synonyms
- Armco
- armedarmed synonyms
- armed forcesarmed forces synonyms
- Armed Forces Day