castile soap

noun

cas·​tile soap (ˌ)ka-ˈstēl- 

variants often Castile soap

: a fine hard bland soap made from olive oil and sodium hydroxide

also : any of various similar soaps

Examples of castile soap in a Sentence

Recent Examples on the Web

The most popular cleaning methods for a menstrual cup include cleaning it with natural products like baking soda or castile soap, submerging it in a sterilizing solution like the type used for baby bottles or boiling it for five to 10 minutes. —Bestreviews, Mercury News, 7 Jan. 2026

After that, treat the plants with organic neem oil or an insecticidal soap spray made by mixing a few drops of castile soap into a quart of water. —Lauren Landers, Better Homes & Gardens, 10 Dec. 2025

Most bands can be cleaned with either dish soap or castile soap and water. —Cody Godwin, USA Today, 14 Sep. 2025

Mop the wall: Using a mixture of warm water and castile soap from a bucket, gently begin mopping the wall vertically. —Kait Hanson, Southern Living, 3 Nov. 2024

Word History

Etymology

Middle English castell sope, from Castell Castile

First Known Use

15th century, in the meaning defined above

Rhymes for castile soap

• electroscope
• heliotrope
• kaleidoscope
• laryngoscope
• ophthalmoscope
• oscilloscope
• polariscope
• stereoscope
• antelope
• bronchoscope
• cantaloupe
• cystoscope

Medical Definition

castile soap

noun

cas·​tile soap (ˌ)kas-ˌtēl- 

: a fine hard bland soap made from olive oil and sodium hydroxide

also : any of various similar soaps