intensify, add, invigorate, fortify, encourage, confirm, increase, multiply, empower, arm, energize, harden, reactivate, steel, reinforce, brace, buttress, stimulate, sustain, nerve, animate, reanimate, restore, reman, refresh, recover, hearten, establish, toughen, temper, bear out, rejuvenate, tone up, build up, make firm, stiffen, brace up, rally, sharpen, enliven, give weight, carry weight, substantiate, uphold, back, augment, enlarge, extend, mount, rise, ascend, wax, grow, back up, beef up*.
Antonyms weaken*, cripple, tear down.
