A model or type of machinery or device which precedes the current (or later) one. Usually used to describe an earlier, outdated model.
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 vertex having a directed path to another vertex
A perennial source of anything; a fountainhead of supply or emanation; resource.
The source of water for a stream, spring or well; a fountainhead; a wellhead.