figurate number

[ fig-yer-it ]
/ ˈfɪg yər ɪt /

noun Mathematics.

a number having the property that the same number of equally spaced dots can be arranged in the shape of a regular geometrical figure.

Origin of figurate number

First recorded in 1605–15 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019