[adj] curving or bulging outward
bell-shaped, biconvex, broken-backed, bulging, convexo-concave, convexo-convex, gibbose, gibbous, hogged, lenticular, lentiform, planoconvex, umbelate, umbellike
concave
arched, arciform, arclike, arcual, bandy, bellied, bellylike, bowed, bowlike, bulging, concave, convexed, embowed, excurvate, excurvated, excurved, gibbose, gibbous, humpbacked, humped, humpy, hunched, hunchy, out-bowed, oxbow, rotund, round, rounded, rou