An Etymological Dictionary of Astronomy and Astrophysics

1. A series or sequence of objects or events.
   

2. A line of coaches or wagons coupled together and drawn by a railway locomotive.

Etymology (EN): M.E., from O.Fr. train “tracks, path, trail; act of dragging,” from trainer “to pull, drag, draw,” from V.L. *traginare, from *tragere “to pull,” back-formation from tractus, p.p. of L. trahere “to pull, draw.”

Etymology (PE): Qatâr “a row of camels,” loan from Ar.; teran, loan from Fr., as above.