castor

1 of 2

noun (1)

cas·​tor ˈka-stər 

1

: beaver sense 1a

2

: castoreum

3

: a beaver hat

Castor

2 of 2

noun (2)

Cas·​tor ˈka-stər 

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

Rosemary, castor, and peppermint oils are known to promote hair growth, and this formula contains all three of them (*chef’s kiss*). —Katie Decker-Jacoby, StyleCaster, 9 July 2024

This 6-fluid ounce budget option keeps frizz down while delivering maximum moisture through ingredients like shea butter, coconut oil, castor and flaxseed oils. —Carrie Honaker, Southern Living, 24 June 2024

Both products are made with heavy oils: castor and jojoba are just a few. —Celeste Polanco, Essence, 20 May 2024

The seat is flanked by a pair of pipe arms, with two castors on the front. —Eric Ravenscraft, WIRED, 15 Apr. 2024

Word History

Etymology

Noun (1)

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

Noun (2)

Latin, from Greek Kastōr

First Known Use

Noun (1)

14th century, in the meaning defined at sense 1

Noun (2)

15th century, in the meaning defined at sense 1

Phrases Containing castor

• castor bean
• castor oil
• castor-oil plant
• castor sugar

Kids Definition

Castor

noun

Cas·​tor ˈkas-tər 

: the more northern of the two bright stars in Gemini

Etymology

Noun

from Greek Kastōr (name of one of the twin heroes in mythology) see Word History at gemini