Definition of skylines:
(n) :
The horizontal silhouette of a city or building against the sky.
(n) :
The line that seems to be the boundary of the sky and the ground; the horizon.
(v) :
(transitive) To outline something against the sky.
(n) :
A path of movement, especially military movement, producing a silhouette above terrain features visible from the location of likely observers.
(n) :
(journalism) A panel on the front page of a newspaper outlining some of the features to be found inside.
(v) :
(databases, transitive) To filter by means of the skyline operator.