flex / fleks/ • v. [tr.] bend (a limb or joint): she saw him flex his ankle and wince. ∎ [intr.] (of a limb or joint) become bent: prevent the damaged wrist from flexing. ∎ cause (a muscle) to stand out by contracting or tensing it: bodybuilders flexing their muscles. ∎ [intr.] (of a muscle) contract or be tensed: a muscle flexed in his jaw. ∎ [intr.] (of a material) be capable of warping or bending and then reverting to shape: set windows in rubber so they flex during an earthquake. ∎ [usu. as adj.] (flexed) Archaeol. place (a corpse) with the legs drawn up under the chin: a flexed burial. • n. the action or state of flexing: add rigidity and eliminate brake flex. PHRASES: flex one's musclessee muscle.