Rules for Adjectives: Gender and Number 1. Adjective ends in -o and is made feminine by changing -o to -a. 2. Adjective ends in -e or in a consonant and does not change with gender of noun. 3. Adjective describing nationality ends in consonant. Add -a for the feminine. 4. Adjective ends in -or, -ón, or -ín. Add -a for the feminine. 5. Adjective is plural and follows the same rules for plurals as nouns. 6. Adjective modifies two nouns of different genders. Masculine plural form is used.