[ kas-ter, kah-ster ]
/ ˈkæs tər, ˈkɑ stər /
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Also castoreum. a brownish, unctuous substance with a strong, penetrating odor, secreted by certain glands in the groin of the beaver, used in medicine and perfumery.
a hat made of beaver or rabbit fur.
a heavy woolen cloth used mainly for coats.
a beaver.
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Origin of castor

1350–1400; Middle English <Latin <Greek kástōr beaver

Other definitions for castor (2 of 2)

[ kas-ter, kah-ster ]
/ ˈkæs tər, ˈkɑ stər /

noun Astronomy.
a star of the second magnitude in the constellation Gemini, the more northerly of the two bright stars in this constellation.

Origin of Castor

Named after Castor;see Castor and Pollux
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

How to use castor in a sentence

British Dictionary definitions for castor (1 of 3)

/ (ˈkɑːstə) /

the brownish aromatic secretion of the anal glands of a beaver, used in perfumery and medicine
the fur of the beaver
a hat made of beaver or similar fur
a less common name for beaver 1 (def. 1)

Word Origin for castor

C14: from Latin, from Greek kastōr beaver

British Dictionary definitions for castor (2 of 3)

/ (ˈkɑːstə) /

a variant spelling of caster (def. 2), caster (def. 3)

British Dictionary definitions for castor (3 of 3)

/ (ˈkɑːstə) /

the second brightest star, Alpha Geminorum, in the constellation Gemini: a multiple star consisting of six components lying close to the star Pollux. Distance: 52 light years
classical myth See Castor and Pollux
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for castor

[ kăstər ]

A bright multiple star in the constellation Gemini, with a combined apparent magnitude of 0.08. Scientific name: Alpha Geminorum.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.