| Arma model | ARMA Tactics | Arma, Kansas |
| Armada Township, Michigan | Armada, Michigan | Armadillidiidae |
| Armageddon | Armageddon (1998 film) | Armagh, Quebec |
| Armak, East Azerbaijan | Armalcolite | Armand Abel |
| Armand Assante | Armand Borel | Armand David |
| Armand Djérabé | Armand Fallières | Armand Lunel |
| Armand Pierre Caussin de Perceval | Armand Traoré | Armand-Emmanuel de Vignerot du Plessis, Duc de Richelieu |
| Armand-Pierre Caussin de Perceval | Armandinho (footballer) | Armando Alonso |
| Armando Álvarez | Armando Castellazzi | Armando Estrada |
| Armando Guebuza | Armando Palacio Valdés | Armando Picchi |
| Armando Riveiro | Armando Visconti | Armando Walle |
| Armando Wila | Armani | Armas Äikiä |
| Armature (electrical engineering) | Armée de terre (France) | Armed forces |
| Armed Forces of the Philippines | Armed Forces of the Republic of the Congo | Armed helicopter |
| Armed Islamic Group of Algeria | Armed neutrality | Armed services |
| Armedlu-ye Sofla | Armel Disney | Armend Dallku |
| Armenia | Armenia, Wisconsin | Armenian constitutional referendum, 2015 |
| Armenian cuisine | Armenian dram | Armenian Genocide |
| Armenian Highlands | Armenian National Academy of Sciences | Armenian Wikipedia |
| Armenian–Azerbaijani War | Armenians | Armenoid race |
| Armie Hammer | Armillaria | Armillaria gallica |
| Armillaria tabescens | Armillary sphere | Armillifer |
| Armillifer armillatus | Armillifer grandis | Armin Mueller-Stahl |
| Armin van Buuren | Armin Veh | Armington, Illinois |
| ARMINIUS VAMBÉRY | Arminius Vambery | Arminius Vámbéry |
| Armistice | Armistice of Cassibile | Armistice of Mudros |
| Armistice of Villa Giusti | Armor hero | Armoracia |
| Armoracia aquatica | Armoracia austriaca | Armoracia lacustris |
| Armoracia macrocarpa | Armoracia natans | Armoracia rusticana |
| Armoracia sisymbrioides | Armoracia valdiviana | Armored Box Launcher |
| Armored car (VIP) | Armour | Armour, South Dakota |
| Armoured bus | Armoured fighting vehicle | Armoured recovery vehicle |
| Armoured train | Armoured vehicle-launched bridge | Armpit fetishism |
| Arms industry | Arms race | Arms trafficking |
| Arms-to-Iraq | Armstrong County, Pennsylvania | Armstrong Creek, Wisconsin |
| Armstrong Siddeley | Armstrong Whitworth Aircraft | Armstrong Whitworth Apollo |
| Armstrong Whitworth Argosy | Armstrong Whitworth Atalanta | Armstrong Whitworth Atlas |
| Armstrong Whitworth AW.660 Argosy | Armstrong Whitworth Ensign | Armstrong Whitworth F.K.8 |
| Armstrong, Iowa | Armstrong, Victoria | Armuture |
| Army | Army Group Centre | Army Group Don |
| Army Group North | Army Men | Army Norway (Wehrmacht) |
| Army of Conquest | Army of Free Lebanon | Army of Islam (Gaza Strip) |
| Army of the Holy War | Army of the Republic of Bosnia and Herzegovina | Army of the Republic of Vietnam |
| Army of Two | Army of Two: The Devil's Cartel | Army Radio |
| Arn Anderson | Arn – The Knight Templar | Arn. |
| Arna's Children | Arnaldo Cézar Coelho | Arnaldo Ortelli |
| Arnaldo Otegi | Arnan, East Azerbaijan | Arnaud Clément |
| Arnaud Dos Santos | Arnaud Le Lan | Arnaud Maire |
| Arnaud Souquet | Arnaut Daniel | Arnór Guðjohnsen |
| Arnbjørn Hansen | Arndale Centre | Arndt Pekurinen |
| Arne Friedrich | Arne Meurman | Arne Tiselius |
| Arnegard, North Dakota | Arnenhorn | Arnica montana |
| Arnie Oliver | Arno Allan Penzias | Arno Dorian |
| Arno Holz | Arno Tausch | Arnold |
| Arnold Badjou | Arnold Bouka Moutou | Arnold Bruggink |
| Arnold Classic | Arnold J. Toynbee | Arnold Mühren |
| Arnold Mvuemba | Arnold O. Beckman | Arnold Palmer |
| Arnold Schwarzenegger | Arnold Sommerfeld | Arnold van Gennep |
| Arnold von Harff | Arnold Wetl | Arnold Wilson |
| Arnold, Nebraska | Arnold, Pennsylvania | Arnold–Chiari malformation |
| Arnoldo Alemán | Arnolds Park, Iowa | Arnoldsville, Georgia |
| Arnolfo di Cambio | Arnolol | Arnoud van Doorn |
| Arnsberg | Arnsberg (region) | Aroideae |
| Aroma Park, Illinois | Aromanian language | Aromat |
| Aromatase | Aromatherapy | Aromatic acid |
| Aromatic compound | Aromatic hydrocarbon | Aromaticity |
| Aron Baynes | Aron Kader | Aron Schmidhuber |
| Aron Winter | Aronia | Aroostook County, Maine |
| Aroser Rothorn | Aroser Weisshorn | Arouna Koné |
| Around the Moon | Around the Pink House | Around the World in 80 Days (1956 film) |
| Around the World in 80 Days (2004 film) | Around the World in Eighty Days | Arousal |
| Arp 116 | Arpanet | ARPANET |
| Arpelistock | Arpin (town), Wisconsin | Arpin, Wisconsin |
| Arquebus | Arques, Pas-de-Calais | Arrabia |
| Arracacia | Arracacia atropurpurea | Arracacia equatorialis |
| Arracacia ovata | Arracacia peruviana | Arracacia rigida |
| Arracacia xanthorrhiza | Arrai TV | Arranged marriage |
| Arrangement | Array data structure | Arraya 2 |
| Arrest and assassination of Ngo Dinh Diem | Arresting gear | Arrhenatherum |
| Arrhenatherum affine | Arrhenatherum album | Arrhenatherum angustifolium |
| Arrhenatherum calderae | Arrhenatherum elatius | Arrhenatherum ilievii |
| Arrhenatherum intermedium | Arrhenatherum kotschyi | Arrhenatherum longifolium |
| Arrhenatherum palaestinum | Arrhenatherum pallens | Arrhenatherum paulianum |
| Arrhenatherum phaenoneuron | Arrhenatherum pragense | Arrhenatherum rupestre |
| Arrhenatherum scabrinsculum | Arrhenatherum scabrum | Arrhenatherum submuticum |
| Arrhenatherum sylvaticum | Arrhenia lobata | Arrhenius equation |
| Arrhenius plot | Arrhythmia | Arrhythmogenic right ventricular dysplasia |
| Arrian | Arriba, Colorado | Arrietty |
| Arrigo Sacchi | Arrondissement | Arrondissements of France |
| Arrow | Arrow (Israeli missile) | Arrow (TV series) |
| Arrow 3 | Arrow Emblem: Hawk of the Grand Prix | Arrow of time |
| Arrow Point, Missouri | Arrow Rock, Missouri | Arrow Sport |
| Arrowsmith (film) | Arrowsmith, Illinois | Arroyomolinos |
| ARS | Arsanilic acid | Arsène Lupin |
| Arsène Wenger | Arsen Avetisyan | Arsenal F.C. |
| Arsenic | Arsenic acid | Arsenic contamination of groundwater |
| Arsenic pentachloride | Arsenic pentoxide | Arsenic tribromide |
| Arsenic trichloride | Arsenic triiodide | Arsenic trioxide |
| Arsenic triselenide | Arsenic trisulfide | Arsenic(III) chloride |
| Arsenic(V) oxide | Arsenide | Arsenopyrite |
