[1] : The Collaborative International Dictionary of English v.0.48

widen \wid"en\, v. t. imp.  p. p. widened; p. pr.  vb. n.
   widening.
   to make wide or wider; to extend in breadth; to increase the
   width of; as, to widen a field; to widen a breach; to widen a
   stocking.
   1913 webster
see also:
widened widening 

[2] : The Collaborative International Dictionary of English v.0.48

widen \wid"en\, v. i.
   to grow wide or wider; to enlarge; to spread; to extend.
   1913 webster

         arches widen, and long aisles extend.    --pope.
   1913 webster

[3] : WordNet (r) 2.0

widen
     v 1: become broader or wider or more extensive; "the road
          widened" ant: narrow
     2: make clothes larger; "let out that dress--i gained a lot
        of weight" syn: let out ant: take in
     3: make wider; "widen the road"
     4: extend in scope or range or area; "the law was extended to
        all citizens"; "widen the range of applications"; "broaden
        your horizon"; "extend your backyard" syn: broaden, extend
see also:
narrow let out take in broaden extend 

[4] : Moby Thesaurus II by Grady Ward, 1.0

88 moby thesaurus words for "widen":
   accrue, accumulate, add to, advance, aggrandize, amplify,
   appreciate, augment, balloon, bloat, blow up, boom, branch,
   branch out, breed, broaden, build, build up, bulk, bulk out,
   crescendo, deal in generalities, deepen, deploy, develop, dilate,
   disperse, distend, ecumenicize, enlarge, expand, extend, fan,
   fan out, fill out, flare, gain, gain strength, generalize,
   get ahead, globalize, go up, greaten, grow, hike, hike up, huff,
   increase, inflate, intensify, magnify, make a generalization,
   mount, multiply, open, open up, outspread, outstretch, overgrow,
   overrun, proliferate, puff, puff up, pump, pump up, raise, ramify,
   rarefy, rise, run up, shoot up, snowball, splay, spraddle,
   sprangle, sprawl, spread, spread like wildfire, spread out,
   strengthen, stretch, sufflate, swell, tumefy, unfold, universalize,
   up, wax

Widen >> W Words
Widen, definition of term: Widen
widen_pag1.html