Word Study
castile soap
CIDE DICTIONARY
castile soap, [From Castile , or Castilia , a province in Spain, from which it originally came.].
A kind of fine, hard, white or mottled soap, made with olive oil and soda; also, a soap made in imitation of the above-described soap. [1913 Webster]
OXFORD DICTIONARY
castile soap, n. a fine hard white or mottled soap made with olive oil and soda.
Etymology
as CASTILIAN
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