Learner's definition of SIMPLICITY
1 [noncount] : the quality of being easy to understand or use
People like the simplicity of the instructions/camera.
For simplicity's sake [=to make it simpler and easier], we have rounded off the numbers to the nearest whole number. = We have rounded off the numbers for the sake of simplicity.
2 a [noncount] : the state or quality of being plain or not fancy or complicated b [count] : something that is simple or ordinary but enjoyable — usually plural 3 [noncount] : something that is easy to do