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

willful \will"ful\, a. will + full. written also wilful.
   1913 webster
   1. of set purpose; self-determined; voluntary; as, willful
      murder. --foxe.
      1913 webster

            in willful poverty chose to lead his life.
                                                  --chaucer.
      1913 webster

            thou to me
            art all things under heaven, all places thou,
            who, for my willful crime, art banished hence.
                                                  --milton.
      1913 webster

   2. governed by the will without yielding to reason;
      obstinate; perverse; inflexible; stubborn; refractory; as,
      a willful man or horse.
      1913 webster -- will"fully, adv. -- will"fulness,
      n.
      1913 webster
see also:
will"fully will"fulness 

[2] : WordNet (r) 2.0

willful
     adj 1: done by design; "the insult was intentional"; "willful
            disobedience" syn: intentional, wilful
     2: habitually disposed to disobedience and opposition syn: froward,
         headstrong, self-willed, wilful
     3: by conscious design or purpose; "intentional damage"; "a
        knowing attempt to defraud"; "a willful waste of time"
        syn: deliberate, intentional, knowing, wilful
see also:
intentional wilful froward headstrong self-willed deliberate 
knowing 

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

133 moby thesaurus words for "willful":
   advised, aimed, aimed at, arbitrary, autonomous, balking, balky,
   bigoted, bulldogged, bulletheaded, bullheaded, calculated,
   case-hardened, conscious, considered, contemplated, contumacious,
   decided, deliberate, deliberated, designed, determined,
   discretional, discretionary, disobedient, dogged, dogmatic,
   elective, envisaged, envisioned, factious, fanatic, free,
   free will, froward, gratuitous, hardheaded, headstrong, heady,
   independent, indisciplined, insubordinate, intended, intentional,
   intolerant, intractable, irresponsible, knowing, lawless,
   licentious, meant, meditated, mulish, mutinous, naughty,
   nonconforming, nonmandatory, obstinate, of design, offered,
   opinionated, optional, overzealous, persevering, pertinacious,
   perverse, pigheaded, planned, proffered, projected, proposed,
   purposed, purposeful, purposive, rampant, recusant, reinless,
   resolved, restive, self-acting, self-active, self-determined,
   self-determining, self-willed, set, spontaneous, stiff-necked,
   strong-willed, strongheaded, stubborn, studied, sulky, sullen,
   teleological, tenacious, transgressive, unaccountable, unasked,
   unbesought, unbidden, unbridled, uncalled-for, unchecked,
   uncoerced, uncompelled, uncomplying, uncontrolled, uncooperative,
   uncurbed, undisciplined, unduteous, undutiful, unforced,
   ungoverned, uninfluenced, uninvited, unpressured, unprompted,
   unregenerate, unreined, unrequested, unrequired, unrestrained,
   unsolicited, unsought, violative, voluntary, volunteer, wayward,
   wildcat, willing, witting, wrongheaded

Willful >> W Words
Willful, definition of term: Willful
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