Cas.to/r |ˈkastər|

1 Greek Mythology the twin brother of Pollux. See Dioscuri.

2 Astronomy the second brightest star in the constellation Gemini, close to Pollux. It is a multiple star system, the three components visible in a moderate telescope being close binaries.

cas.to/r |ˈkastər|
noun

a reddish-brown oily substance secreted by beavers, used in medicine and perfumes.

ORIGIN late Middle English (in the sense [beaver]): from Old French or Latin, from Greek kastōr.