The term 'adaptability' is used to describe a structure that has been constructed to allow modification at minimum cost, to suit the changing needs of the people in the house.
The functions of a house don't change; we eat, sleep and spend our private lives in them. What does change over time is our lifestyle and needs. Some of us may wish to run a business from home; others, as we grow older, want to look after grandchildren, or may need assistance either from mechanical aids or carers.
In any case, living in an adaptable home gives the assurance that we will not be forced to move to another more accommodating residence as our circumstances change.