predecessor

Etymology

From Middle English predecessour, from Old French predecesseor (“forebear”), from Late Latin praedēcessor, from Latin prae- (“pre-”) + Latin dēcessor (“retiring officer”), from Latin dēcēdō (“I retire, I die”) (English decease).

noun

1. 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.
   (rare) ancestor (rare)
2. A model or type of machinery or device which precedes the current (or later) one. Usually used to describe an earlier, outdated model.
   The steam engine was the predecessor of diesel and electric locomotives.
   No. 6959 is painted in the standard wartime black livery and, like its immediate predecessors, does not carry a nameplate, but the words "Hall Class" have been painted on the middle coupled-wheel splasher. 1944 November and December, “Modified G.W.R. "Hall" Class Locomotives”, in Railway Magazine, page 350
3. (mathematics) A vertex having a directed path to another vertex