Greenway Defined
1. A linear open space established along either a natural corridor, such as a riverfront, stream valley, or ridgeline, or overland along a railroad right-of-way converted to recreational use, a canal, a scenic road, or other route.

2. Any natural or landscaped course for pedestrian or bicycle passage.

3. An open-space connector linking parks, nature reserves, cultural features, or historic sites with each other and with populated areas.

4. Locally, certain strip or linear parks designated as a parkway or greenbelt. [American neologism: green+way; origin obscure.]

Charles E. Little, Greenways For America, (The John Hopkins University Press, 1990), p. 2.

Anatomy of a Greenway System
A greenway network can be distilled to three basic parks, links, hubs, and sites.

Links
Links are the heart of the greenway system.  They are the linear connections for people and wildlife.

Hubs
Hubs are the anchors of the system, they provide a base of destination for people and wildlife.

Sites
Sites are smaller features than hubs that serve as points of interest, origins, or destinations.