One who precedes; one who has preceded another in any state, position, office, etc.; one whom another follows or comes after, in any office or position.
A model or type of machinery or device which precedes the current (or later) one. Usually used to describe an earlier, outdated model.
A vertex having a directed path to another vertex
An innovative leader in a field; a pioneer.
One that blazes a trail to guide others; a pathfinder.