The common weasel, little weasel, or simply weasel (Mustela nivalis), the smallest member of the weasel genus Mustela, native to Eurasia, North America, and North Africa.
A snake, especially a large or dangerous one.
An obsolete wind instrument in the brass family, whose shape is suggestive of a snake (Wikipedia article).
A kind of firework with a serpentine motion.
A subtle, treacherous, malicious person.