noun (1)
cas·​tor | \ ˈka-stər How to pronounce castor (audio) \

Definition of castor

 (Entry 1 of 2)

2 : castoreum
3 : a beaver hat


noun (2)
Cas·​tor | \ ˈka-stər How to pronounce Castor (audio) \

Definition of Castor (Entry 2 of 2)

1 : one of the Dioscuri
2 : the more northern of the two bright stars in Gemini

Examples of castor in a Sentence

Recent Examples on the Web: Noun Its Cloudneo shoe, made partially from castor beans, was released around the same time and billed as the first fully recyclable performance running shoe. Steve Larese, Outside Online, 16 Sep. 2022 Those ingredients include rosemary, castor, tea tree and peppermint oil, which is known for soothing. April Franzino, Good Housekeeping, 16 Sep. 2022 Matt continues that castor or argan oil, like Briogeo’s formula, can give weight to flyaways to help lay them down. Kiana Murden, Vogue, 10 Aug. 2022 Expect pillowy soft lips all day long with a potent mix of oils derived from castor seed, sweet almond, jojoba, and so much more. Sarah Han, Allure, 30 June 2022 Glossier's balms are made with natural ingredients like castor seed oil, beeswax, and lanolin. Elizabeth Berry, Woman's Day, 26 July 2022 This antioxidant-rich option is formulated with coffee, caffeine, castor seed, and argan oil to stimulate hair growth at the follicle. Kiana Murden, Vogue, 19 July 2022 Shea butter and coconut and castor oils are all excellent emollients that will detangle hair, seal the cuticle and create more shine and less frizz. Dori Price, Good Housekeeping, 3 June 2022 Developed and patented by Swatch, Bioceramic amalgamates a polymer made from the oil of castor beans with zirconium oxide, a ceramic substance used for scratch-proof, robust, hypoallergenic cases in high-end watchmaking. Tim Barber, Wired, 18 July 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'castor.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of castor

Noun (1)

14th century, in the meaning defined at sense 1

Noun (2)

15th century, in the meaning defined at sense 1

History and Etymology for castor

Noun (1)

Middle English, from Latin, from Greek kastōr, from Kastōr Castor

Noun (2)

Latin, from Greek Kastōr

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Time Traveler for castor

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The first known use of castor was in the 14th century

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Dictionary Entries Near castor



castor bean

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Statistics for castor

Last Updated

20 Sep 2022

Cite this Entry

“Castor.” Dictionary, Merriam-Webster, Accessed 1 Oct. 2022.

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Thesaurus: All synonyms and antonyms for castor Encyclopedia article about castor


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