trailer Definition

trailer
noun

1. A cart, usually with two wheels, that can be hooked up behind a car, etc, and which is used for carrying small loads, transporting small boats, etc.
2. The rear section of an articulated lorry, as opposed to the tractor unit.
(N Amer)
3. A caravan.
4. cinema.TV.radio.
A preview or foretaste, in the form of a brief excerpt or series of such excerpts from a film, programme, etc, that serves as advance publicity before its release or showing.
5. Someone or something that trails behind.

verb

trailered, trailering
1. cinema.TV.radio.
To advertise (a film, programme, etc) with a trailer.

Etymology: 19c: from trail, except noun sense 4 and verb which date from 1920s, so called because in the cinema ‘trailers' were shown after the main programme.