N. quaternity, four, tetrad, quartet, quaternion, # square, quarter, tetract, tetragon, quadrangle, rectangle, tetrahedron, quadrature, quadrifoil, quadriform, quadruplet, quatrefoil, tetrapod, quadrangle, quad, quadrupole, quadrivium

V. reduce to a square, square

Adj. four, quaternary, quaternal, quadratic, quartile, tetract, tetractic, tetractinal, tetrad, tetragonal, square, quadrate

N. angularity, angularness, aduncity, angle, cusp, bend, fold, notch, fork, bifurcation, elbow, knee, knuckle, ankle, groin, crotch, crutch, crane, fluke, scythe, sickle, zigzag, kimbo, akimbo, corner, nook, recess, niche, oriel, coign, right angle, 212, obliquity, angle of 45x, miter, acute angle, obtuse angle, salient angle, reentering angle, spherical angle, angular measurement, angular elevation, angular distance, angular velocity, trigonometry, goniometry, altimetry, clinometer, graphometer, goniometer, theodolite, sextant, quadrant, dichotomy, triangle, trigon, wedge, rectangle, square, lozenge, diamond, rhomb, rhombus, quadrangle, quadrilateral, parallelogram, quadrature, polygon, pentagon, hexagon, heptagon, octagon, oxygon, decagon, pyramid, cone, platonic bodies, cube, rhomboid, tetrahedron, pentahedron, hexahedron, octahedron, dodecahedron, icosahedron, eicosahedron, prism, pyramid, parallelopiped, curb roof, gambrel roof, mansard roof

V. bend, fork, bifurcate, crinkle

Adj. angular, bent, crooked, aduncous, uncinated, aquiline, jagged, serrated, falciform, falcated, furcated, forked, bifurcate, zigzag, furcular, hooked, dovetailed, knock kneed, crinkled, akimbo, kimbo, geniculated, oblique, fusiform, wedge-shaped, cuneiform, cuneate, multangular, oxygonal, triangular, trigonal, trilateral, quadrangular, quadrilateral, foursquare, rectangular, square, multilateral, polygonal, cubical, rhomboid, rhomboidal, pyramidal