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 Usually used to describe an earlier, outdated model.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
The removal of an edge of crystal, by one plane or more.
A person or thing that takes the place of another; a substitute.
The act of replacing something.