a. [f. L. undecim eleven.] Characterized in some way by the number eleven.
1804. Shaw, Gen. Zool., V. i. 24. Undecimal Silure … Silure with single dorsal fin of eleven rays.
1845. Encycl. Metrop., XXV. 1397/1. The numeration [of the New Zealanders] is undecimal by successive multiples of eleven.
