asynchronous
adjective uk/eɪˈsɪŋ.krə.nəs/ us/eɪˈsɪŋ.krə.nəs/
formal不同时存在；不同时发生的
not happening or done at the same time or speed
an asynchronous online course that can be followed from anywhere in the world 无论身在何处，都可以参加异步网上课程的学习
Opposite: synchronous