Definition of top-down:
(adj) :
Of or relating to a hierarchical system that progresses from a single, large basic unit to multiple, smaller subunits.
(adj) :
Produced, controlled, or directed by those at the top of the hierarchy (the upper echelons).
(adj) :
(video games) Presenting the player with an aerial view.
(adj) :
(automotive) Of a drop top, with the convertible top down.