quaternity(n = noun.quantity) 4, four, foursome, iv, little joe, quadruplet, quartet, quatern, quaternary, quaternion, tetrad - the cardinal number that is the sum of three and one;
is a kind of digit, figure

1.  The number four. Sir T. Browne. [1913 Webster]

2.  The union of four in one, as of four persons; -- analogous to the theological term trinity. [1913 Webster]

N  quaternity, four, tetrad, quartet, quaternion, square, quarter, tetract, tetragon, quadrangle, rectangle, tetrahedron, quadrature, quadrifoil, quadriform, quadruplet, quatrefoil, tetrapod, quadrangle, quad, quadrupole, quadrivium, four, quaternary, quaternal, quadratic, quartile, tetract, tetractic, tetractinal, tetrad, tetragonal, square, quadrate.