Concordancia del género del adjetivo

1. Adjectives ending in -o will also end in -o when they describe a masculine noun.
2. Adjectives ending in -o will end in -a when they describe a feminine noun.
3. Adjectives ending in -e or most consonants will not change to reflect gender.
4. Adjectives ending in -or will also end in -or when they describe a masculine noun, but they will end in -ora when describing a feminine noun.

Ejemplos: 

• Un amigo: cómico, inteligente, trabajador, joven
• Una amiga: cómica, inteligente, trabajadora, joven

Concordancia del número del adjetivo

1. If the adjective ends in a vowel, add -s to make the adjective plural.
2. If the adjective ends in a consonant, add -es to make the adjective plural.
3. Just like you learned with nouns ending in -z, if an adjective ends in -z, change the z to c and then add -es to make the adjective plural.

Ejemplos: 

• Un amigo: cómico, inteligente, trabajador, feliz, joven
• Unos amigos: cómicos, inteligentes, trabajadores, felices, jóvenes*
  
  
• Una amiga: cómica, inteligente, trabajadora, feliz, joven
• Unas amigas: cómicas, inteligentes, trabajadoras, felices, jóvenes*

*Joven (young) is our only adjective for now that adds an accent to the plural form.

Posición de los adjetivos

In Spanish, descriptive adjectives follow the noun they describe rather than preceding the noun, as in English.

• Una clase interesante -VERSUS- An interesting class

Adjectives of quantity, however, will precede the noun they modify.

• Tengo mucha tarea. / I have a lot of homework.
• Hay veinticinco estudiantes en la clase de español. / There are twenty-five students in Spanish class.

Some adjectives may be used before or after the noun they describe. Three of these adjectives are bueno (good), malo (bad), and grande (big, large).

When bueno and malo are used before a singular masculine noun, they shorten to buen and mal.

• Un amigo bueno / Un buen amigo
• Una amiga buena / Una buena amiga
• Un día malo / Un mal día
• Una semana mala / Una mala semana

When grande is used before any noun, singular or feminine, it is shortened to gran. However, grande changes meaning depending upon the position relative to the noun. When grande follows the noun, it means big/large, but when gran is used before the noun, it means great/famous.

• Un edificio grande / A big building -VERSUS- Un gran edificio / A great or famous building
• Una clase grande / A big class -VERSUS- Una gran clase / A great class

Listado de adjetivos

When you are listing multiple adjectives to describe a particular noun, you can use commas, y (and), or o (or). Note that each adjective must reflect the number and gender of the noun it describes.

• La profesora es simpática, paciente y trabajadora. / The professor is nice, patient, and hardworking.
• ¿El profesor es alto o bajo?/ Is the professor tall or short?

When y is used before a word beginning in i or hi, change the y to e.

• Mi amiga es simpática e introvertida. / My friend is nice and introverted.

When o is used before a word beginning in o or ho change the o to u.

• Hay siete u ocho clases de español 101 y 102. / There are seven or eight Spanish 101 and 102 classes.