形容詞 willful:

1. done by design
   同義詞：intentional, wilful
2. habitually disposed to disobedience and opposition
   同義詞：froward, headstrong, self-willed, wilful

1. A willful man must have his way.
   [諺]只要人有恒，萬事皆可成。
2. Given to recalcitrant behavior; willful or perverse.
   頑固的，任性的好與人作對(duì)的; 執(zhí)拗的或故意作對(duì)的
3. Given to or marked by willful, often perverse deviation from what is desired, expected, or required in order to gratify one's own impulses or inclinations.
   任性的具有或以任性為特征的，通常與為了滿足某人自己的沖動(dòng)或癖好所期待、盼望或要求的完全相反

willful 也作 wil.ful

adj.（形容詞）
Said or done on purpose; deliberate.See Synonyms at voluntary
故意的：故意說的或做的；存心的，有意的參見 voluntary
Obstinately bent on having one`s own way.See Synonyms at unruly
固執(zhí)的，任性的：頑固地按自己的方式的參見 unruly

【引伸】
will.fully
adv.（副詞）
will.fulness
n.（名詞）