Definition of sierras:
(n) :
A rugged range of mountains.
(n) :
(uncountable) A relatively low-quality grade of Spanish saffron.
(n) :
A scombroid fish.
(n) :
A female given name of modern American usage, from the Spanish noun, confused with Ciara and Sarah.
(n) :
A surname from Spanish.
(n) :
(international standards) Alternative letter-case form of Sierra from the NATO/ICAO Phonetic Alphabet.