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，任性的好與人作對的; 執(zhí)拗的或故意作對的
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）