1. trio, a cardinal number that is equal to the total of the numbers one, one, and one. 3, deuce-ace, III, tercet, ternary, ternion, terzetto, three, threesome, trey, triad, trine, trinity, triplet, troika, tierce, and leash are all other names for the number three. digit, also known as a figure, is one of the components that, when put together, make up a system of numeration; the digits 0 and 1