cubecubecubescubedcubingnoun1a shape like a box with six square sides all the same size2the number that you get if you multiply a number by itself twice: The cube of 5 (= 5³) is 125 (= 5 x 5 x 5).▶ cubicadjective: a cubic metre (= a space like a cube that is one metre long on each side)