| blue mussel | mejillón |
| Blue Nile | Nilo Azul |
| Blue note | Nota de blues |
| Blue object | Objeto azul |
| Blue pickerel | Sander lucioperca |
| Blue Planet | tierra |
| Blue print | Azul |
| Blue Riband | Banda Azul |
| Blue Ridge Mountains | Blue Ridge Mountains |
| blue screen of death | pantalla azul de la muerte |
| Blue Seed | Blue Seed |
| blue shark | tintorera |
| Blue shift | Corrimiento al azul |
| Blue Sky with a White Sun | Emblema de la República de China |
| Blue star | Estrella azul |
| blue stone | azurita |
| blue straggler | estrella rezagada azul |
| blue supergiant | supergigante azul |
| Blue Tegu | Tupinambis merianae |
| blue tit | herrerillo común |
| Blue Train | Blue Train |
| Blue Velvet | Blue Velvet |
| Blue Whale | Balaenoptera musculus |
| Blue Wizards | Magos Azules |
| Blue Öyster Cult | Blue Öyster Cult |
| Blue-and-yellow Macaw | Ara ararauna |
| Blue-bellied Roller | Coracias cyanogaster |
| Blue-billed Duck | Oxyura australis |
| blue-black | azul oscuro |
| blue-chip securities | acciones selectas |
| blue-collar worker | obrero |
| Blue-crowned Parakeet | Aratinga acuticaudata |
| blue-eyed | de ojos azules |
| Blue-eyed grass | Sisyrinchium |
| Blue-eyed soul | Blue eyed soul |
| Blue-footed Booby | Sula nebouxii |
| Blue-fronted Amazon | Amazona aestiva |
| blue-green alga | alga verde-azul |
| Blue-headed Wood-dove | Turtur brehmeri |
| blue-pencil | eliminar |
| Blue-throated Macaw | Ara glaucogularis |
| Blue-tongued skink | Tiliqua |
| Blue-winged Goose | Cyanochen cyanopterus |
| Blue-winged Macaw | Primolius maracana |
| Blue-winged Teal | Anas discors |
| Bluebeard | Barba Azul |
| bluebell | campanilla |
| blueberry | arándano |
| bluebird | pájaro azul |
