It is very common for adjectives in Spanish to take the place of nouns. Study the following examples.
|El viejo no está en el hospital.||The old man is not in the hospital.|
|El joven asiste a la escuela.||The young boy attends school.|
|La joven prepara la lección.||The young girl prepares the lesson.|
|Los ciegos estudian en la universidad.||The blind study at the university.|
To write el hombre viejo, el muchacho joven, or las personas ciegas would normally be considered redundant. Although you may encounter it, it is much more common to see the noun omitted and the adjective used in its place.
amar- to love
deber- to owe; ought, should*
mantener- to maintain, to keep up; to support financially**
la botánica- botany
el/la médico/-a- doctor, physician
el/la novio/-a- boyfriend, girlfriend, fiancé, fiancée
la patria- country, native land, homeland
la tontería- nonsense, silliness, foolishness
cierto- (a) certain
largo- long (false friend)
mismo- same, very
semejante- similar, such
tal- such, such a
tonto- silly, stupid
*Deber is not a synonym of tener que, which indicates strong obligation or necessity. Although they are at times quite close in meaning, deber tends to be “softer,” indicating what one should or ought to do.
**Mantener has all of the irregularities of tener, in the present tense, as well as others to be studied later.