What does "tram" mean?

Additional senses

1. 2.One of the rails of a tramway.
2. 3.A car on a horse railroad. [Eng.] Tram car, a car made to run on a tramway, especially a street railway car. -- Tram plate, a flat piece of iron laid down as a rail. -- Tram pot (Milling), the step and support for the lower end of the spindle of a millstone.
3. 4.A silk thread formed of two or more threads twisted together, used especially for the weft, or cross threads, of the best quality of velvets and silk goods.