the quality of consisting of separate parts that, when combined, form a complete whole

A system lacks modularity when a tweak to one of its components affects the functioning of others. 如果对系统的一个部件的调整影响到其他部件的功能，那么这个系统就缺乏模块化。

The modularity of this design means you can buy a second battery and put that in to keep your doorbell functional while the other charges. 这种模块化设计意味着你可以购买第二块电池，在另一块电池充电时，把它放进去以继续使用门铃。