1 The adjectives agree in gender and number with the noun or pronoun they qualify.
Él es simpático.
Ella es simpática.
Él es irlandés.
Ella es irlandesa.
Some nouns and pronouns do not havea marked gender; in this case, the sex of the person qualified must be taken into account.
Yo soy testarudo (o testaruda).
Su majestad está muy apenado (o apenada).
2 Adjectives of invariable gender
Generally, the adjectives ending in a, e, i, l, s and z are of invariable gender, except the adjectives of place: inglés, inglesa, etc.
Un pueblo salvaje
Una cabra salvaje
Él es comunista.
Ella es comunista.
- Among the adjectives ending in -a a we find the ending in -ícola: agrícola, avícola, vinícola, hortícola, cavernícola; the ending in -ista: deportista, artista, pacifista, elitista, penalista, imperialista, progresista, socialista, comunista, capitalista, populista; también indígena, homicida, cosmopolita, hipócrita. Among the adjectives ending in -a there are some adjectives of place: persa, croata, israelita, belga, maya, celta. Also colour adjectives: lila, rosa, púrpura, malva, escarlata.
- The gender of the adjectives ending in -ble: amable, creíble, agradable, probable; also -bre: salubre, pobre; -ante: constante, importante; -ente latente, insolente, sonriente, patente, independiente; and the adjectives of place ending in -(i)ense: pacense, castellonense.
Are also invariable: breve, árabe, salvaje, torpe, ilustre, dulce, humilde, limítrofe, pusilánime, terrestre, triste.
- The ending in -i: baladí, cursi, israelí, marbellí, marroquí, carmesí, ceutí.
- The ending in -ú: hindú, zulú, bantú.
- The ending in some consonants: -az, -iz y -oz: audaz, contumaz, feliz, veloz, feroz, precoz, voraz, atroz; the llanos adjectives ending in -al o -ar: elemental, fundamental, total, ideal, provenzal, lunar, celular, balear, peninsular; and the llanos or agudos adjectives ending in -il: pueril, ágil, pueril, débil, fácil, dúctil, varonil. The comparative adjectives are invariable and also other adjectives ending in -or: mayor, menor, peor, mejor, superior, inferior, inferior, exterior, anterior, posterior, bi-color. Some invariable adjectives may also function as nouns: gris, azul, verde, cruel, mártir, virgen.
3 Adjectives of variable gender
The adjectives with variable gender may build the feminine according to one of these procedures:
- The masculine ending in -o, -ete and -ote change the last vowel to a.
| Guapo | Guapa |
| Regordete | Regordeta |
- The adjectives ending in consonant add a.
| Pequeñín | Pequeñina |
| Grandullón | Grandullona |
| Chillón | Chillona |
| Holgazán | Holgazana |
| Receptor | Receptora |
Also the adjectives of place ending in -és, -uz, -án, and -in.
| Cordobés | Cordobesa |
| Francés | Francesa |
| Andaluz | Andaluz |
| Alemán | Alemana |
| Catalán | Catalana |
| Mallorquín | Mallorquina |
| Menorquín | Menorquina |
4 Number of the qualifying adjectives
- The adjectives ending innot stressed vowel add -s in the plural: bueno, buenos; cursi, cursis.
- The adjectives ending instressed vowel or consonant add -es in the plural: ideal, ideales; ceutí, ceutíes. The qualifying adjectives ending in -z, form the plural in -ces: veloz, veloces, feroz, feroces. In fact they follow the former rule.
- The adjectives of variable gender have two plural forms: one for the feminine and another for the masculine.
| Pastel bueno | Pasteles buenos |
| Galleta buena | Galletas buenas |
| Hombre guapo | Hombres guapos |
| Mujer guapa | Mujeres guapas |
The adjectives of invariable gender have one form of plural:
| Vestido azul | Vestidos azules |
| Camisa azul | Camisas azules |
- Cortés and descortés have invariable gender and number:
| Hombre descortés | Hombres descortés |
| Mujer descortés | Mujeres descortés |
5 The nouns acting as adjectives do not add -s in a plural sense: situaciones límite, palabras clave.