trail·er 
/ˈtreɪlɚ/ noun
plural trail·ers /ˈtreɪlɚ/ noun [count] 1 : a long platform or box with wheels that is pulled behind a truck or car and used to transport things
▪ We helped them load the furniture onto the trailer. ▪ a horse/boat trailer — see also tractor-trailer 2 chiefly US a : a vehicle that can be pulled by a truck or car and that can be parked and used as an office, vacation home, etc.
▪ We parked our trailer [=(Brit) caravan] next to the lake for the summer.
b : mobile home 3 : a selected group of scenes that are shown to advertise a movie : preview
▪ a theatrical trailer
▪ We helped them load the furniture onto the trailer. ▪ a horse/boat trailer — see also tractor-trailer
▪ We parked our trailer [=(Brit) caravan] next to the lake for the summer.
b : mobile home
▪ a theatrical trailer
