The following list of adjectives is special because they don’t follow the regular “-o” and “-a” endings for masculine and feminine forms, respectively; they have only one form for both genders. Check it out.

egoísta - selfish
materialista - materialistic
optimista - optimistic
pesimista - pessimistic
realista - realistic
alegre - happy
amable - kind
eficiente - efficient
elegante - elegant
excelente - excellent
grande - big
horrible - horrible
importante - important
inteligente - intelligent
interesante - interesting
pobre - poor
responsable - responsible
sociable - sociable
triste - sad
valiente - brave

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