As used in this chapter, the following terms shall have the meanings indicated:
A development of single-family detached dwellings or two single-family attached dwellings (herein referred to as "duplexes") which will preserve desirable open spaces, conserve floodplains and wetlands, provide open space recreational parks and lands for other public or quasi-public purposes compatible with residential uses by permitting a reduction of lot size and the application of certain other regulations hereinafter stated without increasing the number of lots, i.e., the gross density, in the total areas to be developed.