| achievable | realizable |
| achieve | llevar a cabo |
| achieved | terminado |
| achievement | realización |
| Achila II | Agila II |
| Achill Island | Isla Achill |
| Achille Castiglioni | Achille Castiglioni |
| Achillea millefolium | Achillea millefolium |
| Achilles | Aquiles |
| Achilles heel | talón de Aquiles |
| Achilles Painter | Aquiles |
| Achilles Tatius | Aquiles Tacio |
| Achilles tendon | tendón de Aquiles |
| Achillobator | Achillobator |
| aching | doliente |
| Achinoam Nini | Ajinoam Nini |
| Acholi | Acholi |
| Achondrites | Acondrita |
| achondroplasia | acondroplasia |
| achoo | ¡achís! |
| achromatic | acromático |
| Achromatin | Acromatina |
| achromatism | acromatismo |
| Achromic | Acromatófilo |
| achy | dolorido |
| Achères-la-Forêt | Achères-la-Forêt |
| Aché | Aché |
| Aciclovir | Aciclovir |
| acid | mordaz |
| Acid amide | Amida |
| Acid attack | Ataque ácido |
| acid deposition | deposición ácida |
| Acid dissociation constant | Constante de acidez |
| Acid Drinkers | Acid Drinkers |
| Acid dye | Colorantes ácidos |
| Acid house | Acid house |
| Acid phosphatase | Fosfatasa alcalina |
| acid rain | lluvia ácida |
| acidic | ácido |
| acidification | acidificación |
| acidify | acidificar |
| acidimeter | acidímetro |
| acidimetry | acidimetría |
| acidities | acidez |
| acidity | acidez |
| acidity degree | grado de acidez |
| Acidizize | Acidificante |
| acidly | agriarse |
| acidophile | acidófilo |
| acidosis | acidosis |
| acidulate | acidular |
| acidulous | acídulo |
| Acigné | Acigné |
| acinaces | acinace |
| Acinos | Acinos |
| Acipenseridae | Acipenseridae |
| Acipenseriformes | Acipenser |
| Acireale | Acireale |
| Acis | Acis |
| ack-ack | artillería antiaérea |
| Ackee | Blighia |
| Ackermann function | Función de Ackermann |
| acknowledge | aceptar |
