| Subject | Spanish | English |
| nat.sc. | aguja azul del Indo-Pacífico | Indo-Pacific blue marlin (Makaira mazara) |
| nat.res. | alga azul-verdosa | cyanobacterium |
| biochem. | algas azul-verdes Cyanophyceae | cyanobacteria |
| biochem. | algas azul-verdes Cyanophyceae | blue-green algae |
| chem. | azul a la cal | lime blue |
| chem., met. | azul alcalino | alkali blue |
| chem. | azul Berlin | Berlin blue |
| chem. | azul Berlín | Berlin blue |
| chem. | azul brema | Bremen blue |
| food.ind., chem. | azul brillante | brilliant blue |
| agric., food.ind., chem. | azul brillante FCF | Brilliant Blue FCF |
| food.ind., chem. | azul brillante FCF | CI food blue 2 |
| food.ind., chem. | azul brillante FCF | E133 |
| food.ind., chem. | azul brillante FCF | brilliant blue FCF |
| agric., food.ind., chem. | azul brillante FCF | E 133 |
| chem. | azul Brunswick | Brunswick blue |
| chem. | azul celeste | sky blue |
| chem. | azul cerúleo | cerulean blue |
| chem. | azul chino | Chinese blue |
| gen. | azul claro | light blue |
| gen. | azul cobalto | cobalt blue |
| med. | azul de aceite | oil blue |
| chem. | azul de Brema | Bremen blue |
| gen. | azul de Bremen | Bremen blue |
| chem. | azul de bromofenol | bromophenol blue |
| chem. | azul de bromotimol | bromothymol blue |
| chem. | azul de cobalto | cobalt blue |
| chem. | azul de cobalto | king's blue |
| chem. | azul de esmalte | enamel |
| lab.eq. | azul de Evans | Evans blue |
| chem. | azul de ftalocianina alfa | alpha blue |
| chem. | azul de ftalocianina beta | beta blue |
| chem. | azul de ftalocianina épsilon | epsilon blue |
| chem. | azul de ftalocionina gamma | gamma blue |
| chem. | azul de indantreno | indanthrone blue |
| chem. | azul de indantreno | indanthrene |
| tech., mater.sc. | azul de indofenol | indophenol blue |
| chem. | azul de lavandería | laundry blue |
| agric. | azul de los vinos blancos | blue sickness of white wines |
| chem. | azul de manganeso | manganese blue |
| chem. | azul de metileno | methylene blue |
| chem. | azul de molibdeno | mineral indigo |
| chem. | azul de molibdeno | molybdenum blue |
| cultur. | azul de montaña | mountain blue |
| chem. | azul de Paris | Parisian blue |
| chem. | azul de Paris | Prussian blue |
| chem. | azul de Prusia | Parisian blue |
| chem. | azul de Prusia | Paris blue |
| chem. | azul de Prusia | milori blue |
| chem. | azul de Prusia | iron blue |
| chem. | azul de Prusia | Prussian blue |
| chem. | azul de Prusia, azul de Berlín | Prussian blue |
| chem. | azul de Prusia, azul de Berlín | Berlin blue |
| health. | azul de quinaldina | quinaldine blue (quinaldinum coeruleum) |
| cultur. | azul de Sajonia | Saxony blue |
| chem. | azul de Sevres | Sevres blue |
| chem. | azul de thenard | cobalt blue |
| chem. | azul de Thénard | Thenard’s blue |
| chem. | azul de Thénard | Thenard's blue |
| chem. | azul de timol | thymol blue |
| chem. | azul de toluidina | tolonium chloride |
| chem. | azul de toluidina | toluidine blue |
| textile | azul de trabajo en sarga | denim |
| chem. | azul de Turnbull | Turnbull's blue |
| industr. | azul de ultramar claro | light ultramarine |
| chem. | azul de vanadio | vanadium blue |
| chem. | azul de índigo | indigotin |
| chem. | azul de índigo | indigo |
| life.sc. | azul del cielo | blue of the sky |
| chem. | azul marino | dark blue |
| chem. | azul marino | navy blue |
| chem. | azul marino | blue |
| earth.sc., el. | azul menos luminancia | blue minus luminance |
| chem. | azul mineral | mineral blue |
| gen. | azul oscuro | dark blue |
| chem. | 2.1 azul pantentado V | Patent Blue V |
| chem. | 2.1 azul pantentado V | E 131 |
| chem. | 2.1 azul pantentado V | 2.1 patent blue |
| chem. | azul patentado V | E 131 |
| chem. | azul patentado V | CI food blue 5 |
| chem. | azul patentado V | 2.1 patent blue |
| chem. | azul patentado V | E131 |
| chem. | azul patentado V | patent blue V |
| chem. | azul patentado V | Patent Blue V |
| food.ind., chem. | azul patente | patent blue |
| chem. | azul patente V | patent blue V |
| chem. | azul patente V | E131 |
| chem. | azul patente V | CI food blue 5 |
| chem. | azul Peligot | Peligot blue |
| chem. | azul pompeyano | Pompeian blue |
| chem. | azul real | king's blue |
| chem. | azul real | cobalt blue |
| cultur. | azul Thenard | Thenard's blue |
| chem. | azul ultramar | French blue |
| chem. | azul ultramar | ultramarine |
| chem. | azul ultramar | ultramarine blue |
| hobby, environ. | bandera azul en Europa | Blue Flag of Europe |
| dril. | capacidad de azul de metileno | methylene blue capacity |
| nat.sc., agric. | chinche azul de la col | cabbage bug (Eurydema oleraceum) |
| entomol. | chinche azul de la col: chinche roja de la col Eurydema oleraceum (L.) | brassica bug |
| entomol. | chinche azul de la col: chinche roja de la col Eurydema oleraceum (L.) | cabbage bug |
| med. | colorante azul de Nil | nile blue stain |
| org.name. | Comisión para la Conservación del Atún de Aleta Azul del Sur | Commission for the Conservation of Southern Bluefin Tuna |
| gen. | El color azul es asociado a menudo con la tristeza | The color blue is often associated with sadness |
| gen. | El color azul predominó en este cuadro | The blue predominated in this paint |
| environ. | ensayo del azul de metileno | stability test |
| gen. | escudo azul y blanco | blue and white shield |
| tech. | filtro del azul negativo | minus blue filter (filtro para eliminar el azul del espectro electromagnético) |
| tech. | fotometría de absorción con azul de metileno | absorption photometry with methylene blue |
| environ., nat.res. | guacamayo azul y dorado | blue and yellow macaw (Ara ararauna) |
| environ., nat.res. | guacamayo azul y dorado | blue and gold macaw (Ara ararauna) |
| gen. | Hay muchos tonos de azul, desde el azul oscuro hasta el azul claro | There are many shades of blue from dark blue to light blue |
| gen. | He optado por un vestido azul para la fiesta | I opted for a blue dress for the party |
| textile | indice de azul de metileno | methylene blue number |
| agric. | mildiúm azul del tabaco | mould |
| agric. | mildiúm azul del tabaco | tobacco blue mould |
| agric. | mildiúm azul del tabaco | downy mildew of tabacco |
| nat.sc., agric. | moho azul de los agrios | mold (Penicillium italicum) |
| nat.sc., agric. | moho azul de los agrios | blue mould of citrus (Penicillium italicum) |
| agric. | moho azul del tabaco | downy mildew of tabacco |
| agric. | moho azul del tabaco | mould |
| agric. | moho azul del tabaco | downy mildew |
| pest.contr. | moho azul del tabaco | downy mildew of tobacco |
| pest.contr. | moho azul del tabaco | tobacco blue mould |
| nat.sc., agric. | moho azul del tabaco | tobacco blue mould (Peronospora tabacina) |
| nat.sc., agric. | moho azul del tabaco | downy mildew of tobacco (Peronospora tabacina) |
| agric. | moho azul del tabaco | blue mould |
| nat.res. | mosca azul de la carne | bluebottle (Calliphora erythrocephala, Lucilia sericata) |
| nat.res. | mosca azul de la carne | bluebottle blowfly (Calliphora erythrocephala, Lucilia sericata) |
| nat.res. | mosca azul de la carne | blow fly (Calliphora erythrocephala, Lucilia sericata) |
| med. | método azul de Prussian | Prussian blue method |
| chem. | papel de filtro impregnado con yoduro potásico almidón que vira al azul al contacto con el ozono | ozone paper |
| nat.sc., agric. | pargo azul dorado | blue and gold snapper (Lutjanus viridis) |
| bot. | pasto azul de Kentucky Poa pratensis | meadow grass |
| bot. | pasto azul de Kentucky Poa pratensis | smooth-stalked meadowgrass |
| agric. | pasto azul de Kentucky | common meadow grass (Poa pratensis) |
| agric. | pasto azul de Kentucky | june grass (Poa pratensis) |
| bot. | pasto azul de Kentucky Poa pratensis | smooth meadow grass |
| nat.res., agric. | pasto azul de Kentucky | Kentucky blue grass (Poa pratensis) |
| nat.res., agric. | pasto azul de Kentucky | smooth meadow-grass (Poa pratensis) |
| bot. | pasto azul de Kentucky Poa pratensis | Kentucky bluegrass |
| bot. | pasto azul del Canadá Poa compressa | Canada bluegrass |
| fish.farm. | pez nariz azul antártico | bluenose warehou (Hyperoglyphe antarctica) |
| fish.farm. | pez nariz azul antártico | Antarctic butterfish (Hyperoglyphe antarctica) |
| construct. | piedra azul, granito de Flandes | petit granit |
| construct. | piedra azul, granito de Flandes | Flanders granite |
| construct. | piedra azul, granito de Flandes | ecaussine |
| construct. | piedra azul, granito de Flandes | Belgian granite |
| vet.med. | piojo azul de cabeza corta Haematopinus eurysternus | short-nosed cattle louse |
| leath. | piojo azul de cabeza larga Linognathus vituli | long-nosed cattle louse |
| org.name. | Plan Azul, Centro de actividades regionales del Plan de Acción para el Mediterráneo | Blue Plan - Regional Activity Centre for the Mediterranean |
| environ., UN | Plan azul para el Mediterráneo | Blue Plan on the Mediterranean |
| environ. | prueba con azul de metileno | stability test |
| environ. | prueba con azul de metileno | methylene blue test |
| pest.contr., Arg. | pulgón azul de la alfalfa Acyrthosiphum kondoi (Shinji) | bluegreen aphid |
| nat.res., agric. | pícea azul de Colorado | blue spruce (Picea pungens glauca koster) |
| comp., MS | rojo, verde, azul, alfa | red, green, blue, alpha (A model that augments the red, green, blue (RGB) method of combining colors in light-based media, with a fourth color component, alpha, which is used to control color blending. In Open GL, an alpha value of 1.0 corresponds to complete opacity and a value of 0.0 corresponds to complete transparency) |
| law, immigr. | tarjeta azul de la UE | EU Blue Card |
| immigr. | tarjeta azul UE | Blue Card |
| immigr., lab.law. | tarjeta azul UE | EU Blue Card |
| textile | tejido para azul mecánico | dungaree |
| environ. | test con azul de metileno | methylene blue test |
| med. | tinción con azul de toluidina | toluidine blue application |
| immigr. | titular de la tarjeta azul UE | Blue Card holder |
| social.sc. | triángulo azul sobre fondo naranja | blue triangle on orange ground |