Definitions of sierra:

• noun:   a Spanish mackerel of western North America
• noun:   a range of mountains (usually with jagged peaks and irregular outline)
• name:  A female given name (rare: 1 in 12500 females; popularity rank in the U.S.: #1006)
• name:  A surname (common: 1 in 14285 families; popularity rank in the U.S.: #1780)