monotony
noun [ U ] uk/məˈnɒt.ən.i/ us/məˈnɑː.t̬ən.i/ (also monotonousness)
单调乏味；毫无变化
a situation in which something stays the same and is therefore boring
The monotony of motorway driving can cause accidents. 在高速公路上驾车单调乏味，可能引发交通事故。
The routine was the same every day, with nothing to break/relieve the monotony. 每天做的事都相同，没有什么来打破／调剂这种单调。