· "Many common adjectives end in -o. These adjectives have four forms. The following words all mean 'tall':
The correct form of the adjective depends upon the noun it modifies. Is the noun masculine or feminine? Singular or plural?
Adjectives that end in -e also change form for singular or plural. To form the plural, simply add -s.
la chica inteligente
las chicas inteligentes
Adjectives that end in -e do not, however, change form for masculine or feminine.