Made of or resembling ivory; having the qualities of ivory such as being white, smooth, and hard.
From Latin ebur (ivory) + -eous (adjectival suffix meaning 'made of or like'). The -eous suffix appears in English in words like 'gorgeous' and 'erroneous'. This Latinate adjective form was common in 18th-century English.
The suffix -eous was the fancy way to say 'made of' in old English—calling something 'eburneous' instead of just 'ivory' was like wearing a three-piece suit instead of casual clothes!
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