A glass of chilled watermelon juice is perfectly thirst-quenching after exercise.

thirst-quenching 是由名词 thirst（口渴）和动词 quench（解渴、熄灭）组成的复合形容词，quench 后面加 -ing 变成现在分词形式。thirst-quenching 字面意思是"解渴的"，形容能有效缓解口渴的感觉。