(n.) A group of four\.

Little Joe biquadrate bout contest decathlon double-header doubles event four four-part diaphony game games of chance go match meet pentathlon play play-off quad quadrangle quadrature quadrennium quadrilateral quadrille quadrinomial quadruplet quartet quatern quaternary quaternion quaternity quatrefoil race rectangle runoff singles sport square square dance squaring tetrad tetragon tetragram tetragrammaton tetrahedron tetralogy tetraphony tetrapody threesome twosome