The term finish to start refers specifically to the logical relationship that exits between the activities that make up he entirety of the project in which it is determined by the project team or the project team leader that the initiation of work on a succeeding schedule work activity is entirely dependent on the formal conclusion of work on a particular activity that directly precedes it. To clarify exactly how that effects the workflow of the activities that make up a specific project, the work on an activity scheduled to follow a previous activity simply cannot begun under any circumstances unless and until the previous activity has been totally completed by the project team, or whomever may be responsible for it. The purposes behind this are many. First, it assures manpower. The same members who are working on one activity may then be able to transition to the next activity. Secondarily, it allows for easier means of keeping track of all activities, and all details, with less chance of any confusion. Quite simply, it is a way or keeping order.’
This term is defined in the 3rd and the 4th edition of the PMBOK.