Strengthen

• POS: Verb (usu participle)
• HYPHEN: strength=en

CIDE DICTIONARY

Strengthen, v. t. 

•  To make strong or stronger; to add strength to; as, to strengthen a limb, a bridge, an army; to strengthen an obligation; to strengthen authority.  [1913 Webster]

  "Let noble Warwick, Cobham, and the rest, . . .
  With powerful policy strengthen themselves."  [1913 Webster]
•  To animate; to encourage; to fix in resolution.  [1913 Webster]

  "Charge Joshua, and encourage him, and strengthen him."  [1913 Webster]

Syn. -- To invigorate; confirm; establish; fortify; animate; encourage.

Strengthen, v. i. 

 To grow strong or stronger.  [1913 Webster]
"The young disease, that must subdue at length,
Grows with his growth, and strengthens with his strength."  [1913 Webster]

OXFORD DICTIONARY

Strengthen, v.tr. & intr. make or become stronger.

Idiom

strengthen a person's hand (or hands) encourage a person to vigorous action.

Derivative

strengthener n.

THESAURUS

Strengthen

accelerate, accrue, accumulate, add to, advance, affirm, aggravate, animate, anneal, appreciate, attest, augment, authenticate, back, back up, balloon, be tough, bear out, beef up, bloat, blow up, bolster, boom, boost, brace, brace up, breed, broaden, buttress, case harden, certify, cheer, chirk up, circumstantiate, complicate, concentrate, condense, confirm, consolidate, corroborate, crescendo, deepen, develop, document, double, embolden, encourage, endure, energize, enhance, exacerbate, exaggerate, fortify, gain, gain strength, gelt, get ahead, gird, go up, grow, hang tough, harden, hearten, heat up, heighten, hop up, hot up, increase, inspirit, intensify, invigorate, jazz up, key up, magnify, make complex, mount, multiply, nerve, nourish, nutrify, prepare, probate, proliferate, prop, prove, ramify, ratify, ready, recruit, redouble, refresh, reinforce, reinvigorate, rejuvenate, renew, restrengthen, rigidify, rise, run up, screw up, sharpen, shoot up, shore up, sinew, snowball, soup up, spread, steel, step up, stiffen, substantiate, supplement, support, sustain, swell, temper, tense, tighten, tone up, toughen, trice up, triple, undergird, uphold, validate, verify, vitalize, warrant, wax, whet, widen

ROGET THESAURUS

Strengthen

Increase

VB increase, augment, add to, enlarge, dilate, grow, wax, get ahead, gain strength, advance, run up, shoot up, rise, ascend, sprout, aggrandize, raise, exalt, deepen, heighten, strengthen, intensify, enhance, magnify, redouble, aggravate, exaggerate, exasperate, exacerbate, add fuel to the flame, oleum addere camino, superadd, spread.

Power

VB be powerful, gain power, belong to, pertain to, lie in one's power, be in one's power, can, be able, give power, confer power, exercise power, empower, enable, invest, indue, endue, endow, arm, strengthen, compel.

Strength

VB be strong, be stronger, overmatch, render strong, give strength, strengthen, invigorate, brace, nerve, fortify, sustain, harden, case harden, steel, gird, screw up, wind up, set up, gird up one's loins, brace up one's loins, recruit, set on one's legs, vivify, refresh, refect, reinforce, reenforce.