| arboreal | arborícola |
| arboretum | arboreto |
| arboriculture | arboricultura |
| Arbouet-Sussaute | Arbouet-Sussaute |
| arbour | caramanchão |
| arboury | pérgula tempo |
| Arbovirus | Arbovirose |
| Arbre | Árvore |
| Arbrissel | Arbrissel |
| Arbuscular mycorrhiza | Glomeromycota |
| Arbutus | Arbutus unedo |
| Arbutus berry | Medronho |
| Arbutus fruit | Medronho |
| Arbérats-Sillègue | Arbérats-Sillègue |
| Arbëreshë | Arbëreshë |
| arc | arco |
| Arc de Triomf | Arco do triunfo |
| Arc minute | Minuto de arco |
| Arc second | Segundo de arco |
| arc welding | arco-soldagem |
| Arcachon | Arcachon |
| arcade | arcada |
| Arcade Fire | Arcade Fire |
| Arcade system board | Placa de arcade |
| arcaded | arcado |
| Arcadia | Arcádia |
| Arcadius | Arcádio |
| Arcady | Arcádia |
| Arcangelo Corelli | Arcangelo Corelli |
| Arcangues | Arcangues |
| Arce - Artzi | Arce |
| Arcelor Mittal | Arcelor Mittal |
| Arceniega | Artziniega |
| arch | traquina |
| Arch Linux | Arch Linux |
| Arch of Constantine | Arco de Constantino |
| Arch of Septimius Severus | Arco de Septímio Severo |
| Arch of Titus | Arco de Tito |
| Arch of Triumph | Arco do triunfo |
| arch support | palmilha ortopédica |
| arch- | arco |
| arch-enemy | arco-inimigo |
| Archaea | Archaea |
| Archaeoastronomy | Arqueoastronomia |
| Archaeobatrachia | Archaeobatrachia |
| Archaeocyatha | Archaeocyatha |
| archaeological | arqueológico |
| Archaeological culture | Cultura material |
| Archaeological industry | Indústria |
| archaeological site | patrimómio arqueológico |
| Archaeological theory | Teoria arqueológica |
| archaeologist | arqueólogo |
| archaeology | arqueologia |
| Archaeology of Israel | Arqueologia de Israel |
| Archaeology of the Americas | Arqueologia das Américas |
| Archaeopteryx | Arqueopterix |
| Archaeplastida | Archaeplastida |
| archaic | antigo |
