As the company grew, he became thirstier for success.

### 解释 thirstier 是形容词 thirsty 的比较级形式。thirsty 本义是"口渴的"，引申为"渴望的、渴求的"。thirstier 表示"更加渴望的"，在这里比喻对成功的强烈追求。