(idiomatic) An occupation or situation that generates considerable income or benefits while requiring little effort and carrying little risk.

railroad track, railway track / (topology) A set of curves lying in a surface, meeting one another at their respective endpoints in a specific way that resembles railroad tracks

The mechanical system that operates the valves in an internal combustion engine.

A train service, running only during a winter sports season, that carries skiers and other tourists to and from a resort.

plural of gravy train

A locomotive plus the carriages that it pulls along a railway track. / A series of railcars/electric multiple units connected together.

To train in a different task, skill or sport / To train in a variety of tasks, skills or sports

(chiefly US) A place where trains stop for passengers to embark and disembark.

plural of train station

(rail transport) A train whose primary function is to carry passengers.