Adjective Agreement: Matching Gender and Number
Quick Answer: Adjectives must agree with their noun in both gender and number. Adjectives ending in -o change to -a for feminine.
Why 'bueno' becomes 'buena', 'buenos', and 'buenas'
Category: Gender & Agreement
The Rule
Adjectives must agree with their noun in both gender and number. Adjectives ending in -o change to -a for feminine. Adjectives ending in -e or a consonant stay the same for gender but add -s/-es for plural.
Why This Matters
In English, adjectives never change form ('a tall man, a tall woman, tall people'). In Spanish, they must match. This means you need four forms for -o adjectives: alto, alta, altos, altas. Adjectives ending in -e (grande) or consonants (fácil) only change for number.
Examples
• El gato negro. / La gata negra. — "The black cat (m). / The black cat (f)." [-o/-a change for gender] • Los libros interesantes. — "The interesting books." [-e adjective: same for m/f, add -s for plural] • Las preguntas fáciles. — "The easy questions." [Consonant adjective: add -es for plural] • Un hombre español. / Una mujer española. — "A Spanish man. / A Spanish woman." [Nationality adjectives ending in consonant add -a for feminine]
Common Mistakes
❌ La casa es bonito. ✅ La casa es bonita. → Casa is feminine, so the adjective must be feminine too: bonita, not bonito. ❌ Los problemas grandes. ✅ Los problemas grandes. → This is actually correct! 'Grande' doesn't change for gender (only number). But the article must be masculine because 'problema' is masculine.
Quick Tip
When an adjective describes a mixed-gender group, use the masculine plural: 'Los niños y las niñas son altos.' The masculine 'wins' in mixed groups.
When an adjective describes a mixed-gender group, use the masculine plural: 'Los niños y las niñas son altos.' The masculine 'wins' in mixed groups.
Examples
Common Mistakes
Incorrect: La casa es bonito. → Correct: La casa es bonita.. Casa is feminine, so the adjective must be feminine too: bonita, not bonito.
Incorrect: Los problemas grandes. → Correct: Los problemas grandes.. This is actually correct! 'Grande' doesn't change for gender (only number). But the article must be masculine because 'problema' is masculine.
Quiz
'The red cars' — which is correct?