Princeton's WordNet

1. jumping-off place, point of departure(noun)

   a place from which an enterprise or expedition is launched

   "one day when I was at a suitable jumping-off place I decided to see if I could find him"; "my point of departure was San Francisco"

2. springboard, jumping-off point, point of departure(noun)

   a beginning from which an enterprise is launched

   "he uses other people's ideas as a springboard for his own"; "reality provides the jumping-off point for his illusions"; "the point of departure of international comparison cannot be an institution but must be the function it carries out"