impetuous 冲动的 impulsive
impulse 冲动 刺激 （pulse脉搏 跳动）
impulsive 易冲动的
On seeing the poor little girl, he has an  impulse to adopt her.
urge 冲动
The girl suppressed an urge to laugh.
incentive 刺激 动机 motivation
People doupt about her incentive to marry  that rich old fellow.
motivation 动机 motive, incentive
Unfortunately his salary is his only  motibation for working.
objective 目标 aim, goal (object客观+ive)