From Middle French castor, from Old French castor (“beaver”), from Latin castor (“beaver”), from Ancient Greek κάστωρ (kástōr), from Doric Greek κάστον (káston, “wood”).
Meanings
(countable, uncountable) A hat made from the fur of the beaver.
I have been always noted for the jaunty manner in which I wear my castor—[…] 1826, [Walter Scott], chapter V, in Woodstock; Or, The Cavalier. […], volume I, Edinburgh: […] [James Ballantyne and Co.] for Archibald Constable and Co.; London: Longman, Rees, Orme, Brown, and Green, →OCLC, page 135:
(countable, uncountable) A heavy quality of broadcloth for overcoats.
(countable, uncountable) Castoreum (bitter exudate of mature beavers).
(countable, uncountable) Any of various nymphalid butterflies of the genus Ariadne, of Africa and Asia.
Alternative spelling of caster, via cast + -or (the Latinate varient of -er).
Meanings
(UK, especially) Alternative spelling of caster, especially in its senses ▸ A pivoting roller attached to the bottom of furniture to allow it to be moved.
(UK, especially) Alternative spelling of caster, especially in its senses ▸ A container with a perforated cap for sprinkling its contents, especially salt, pepper, etc.
Mrs. Hussey soon appeared, with a mustard-pot in one hand and a vinegar-cruet in the other, having just broken away from the occupation of attending to the castors, and scolding her little black boy meantime. 1851 November 14, Herman Melville, “The Ramadan”, in Moby-Dick; or, The Whale, 1st American edition, New York, N.Y.: Harper & Brothers; London: Richard Bentley, →OCLC, page 92: