In West Africa, people have long chewed kola nuts as stimulants, because they contain caffeine that also occurs naturally in tea, coffee, and chocolate.
2017年12月六级真题（第一套）阅读 Section C
柯林斯高阶英汉双解学习词典释义
N-COUNT
兴奋剂;引起兴奋的药物
A stimulant is a drug that makes your body work faster, often increasing your heart rate and making you less likely to sleep.