means A long range of mountains, especially one with a sharp, jagged crest of peaks — and, in some uses, the Spanish word for such ranges.

from From Spanish sierra, meaning literally 'saw,' from Latin serra, 'a saw' — the toothed blade for cutting wood or stone. Spanish speakers looked at rows of sharp peaks and saw a serrated edge biting the sky, so the same word came to mean both the tool and the mountain. The English 'serrated' is a close cousin from that same Latin root.