khat       
noun [ U ] (also qat) uk/kɑːt/ us/kɑːt/
 阿拉伯茶(叶)
the leaves of an Arabian bush, also called khat, that are chewed or made into tea and contain a substance that acts as a stimulant (= a substance that makes the mind or body more active), which is classed as an illegal drug in some countries
  Chewing khat is an ancient tradition in some cultures. 咀嚼阿拉伯茶是某些文化中的古老传统。 
 - More examples
 - Dried khat leaves can be made into tea.
 - Parts of the khat or qat shrub have been used for centuries as a mild stimulant.
 - Fresh khat typically is chewed like loose tobacco, and the juice is swallowed.
 - Cathinone, the key chemical that gives khat its kick, breaks down quickly and vanishes within two to three days.