Disjoint in relation to set logic is when you are given two sets that do not share anything in common at all. Here is a simple example. you have a set A that consists of elements 1,2,3,4 and a set B that consists of elements 5,6,7,8. The two sets do not have any of the same elements thus the two sets are disjoint.

I found that displaying an example of disjoint sets was the easiest out of all the set logic.