1) Practicality 1) Usableness 
qualitative indication of the range or scope of the functions that a system or item of equipment can carry out NOTE - A system that can carry out many complex functions has a 'high functionality' ; a system that can only carry out a few simple functions has a 'low functionality'.
The capability of the software product to provide functions which meet stated and implied needs when the software is used under specified conditions. [ISO 9126]...
[n] - capable of serving a purpose well
functionality 1. The quality of being functional or serving a purpose well. 2. A useful function within a computer application or program. 3. The capacity of a computer program or application to provide a useful function.
noun capable of serving a purpose well; `software with greater functionality`