I. sēˈerə noun
( -s )
Etymology: Spanish, literally, saw, from Latin serra saw
1.
a. : a range of mountains especially with a serrated or irregular outline
the wild sierra overhead, the desert's death below — J.G.Whittier
— often used in plural
never lost sight of the towering sierras — Library of Congress Information Bulletin
north of Lake Tahoe the sierras are divided — W.W.Atwood †1949
b. : a mountainous region
in the sierra , the prevailing pattern among the Indian population is subsistence farming — Internat'l Reference Service
the southern sierra fairly bristles with distinguished art — Scientific Monthly
2. : any of various large fishes (genus Scomberomorus ) that resemble mackerel: as
a. : cero
b. : either of two common Spanish mackerel ( S. maculatus and S. sierra )
3. often capitalized : venetian red 2a
II.
Usage: usually capitalized
— a communications code word for the letter s