Feminine counterparts of masculine adjectives 1

The -o → -a pattern — Most adjectives ending in -o form the feminine by changing to -a: nuevo → nueva, pequeño → pequeña, guapo → guapa. This is the most common pattern and covers the majority of Spanish descriptive adjectives.

Nationality adjectives ending in a consonant — Many nationality adjectives ending in a consonant add -a for the feminine: español → española, francés → francesa, inglés → inglesa. Note that adjectives ending in -és or -án lose their written accent in the feminine form.

One-form adjectives — no change needed — Adjectives ending in -e or most consonants keep the same form for both genders: inteligente, triste, azul, fácil, joven. Only the plural adds -s or -es. Knowing this saves you from inventing forms that don't exist.