Convex rhymes with:
vex, aix, atx, beck's, becks, blech's, caltex, checks, cmx, czechs, dec's, decks, dex, eckes, ex, execs, fedex, flecks, flex, govpx, heck's, hex, jex, lex, meckes, megaplex, mex, necks, nex, nobec's, onex, peck's, perplex, plex, quebec's, rex, sex, sheck's, shek's, specks, specs, tech's, techs, teck's, tex, treks, triplex, vex, wall-tex, wrecks, x, x.
Convex sounds like:
cambex, camby's, camp's, campeau's, campise, campisi, campobasso, campos, camps, camps', campus, campuses, cannabis, canvas, canvases, canvass, canvasses, champoux, champs, chemfix, chimps, combes, combs, comeback, comebacks, compaq, compaq's, compas, compass, compose, composes, compus, compusa, compusa's, confess, confesses, confucius, confuse, confuses, conveys, convoys, coombes, coombs, cumbias