Hours passed and she became impatient and thought he had forgotten about their date.

impatient 是由前缀 im-（表示"不、非"）和形容词 patient（耐心的）组成的形容词，意思是"不耐烦的、急躁的"。前缀 im- 是 in- 的变体，用在以 p 开头的词前。