1train 
/ˈtreɪn/ noun
plural trains /ˈtreɪn/ noun 1 : a group of vehicles that travel on a track and are connected to each other and usually to an engine : a connected group of railroad cars [count] ▪ The train pulled into the station. ▪ You can get off/on the train in Atlanta. ▪ I took a train to Madrid. ▪ We caught the last train. ▪ We slept on the train. ▪ a passenger train [=a train that people use for traveling] ▪ a commuter train [=a train that people use to get to and from work] ▪ an express train [=a train that has very few stops] ▪ a subway train [=an underground train] ▪ (US) a freight train = (Brit) a goods train [=a train carrying cargo] [noncount] ▪ We traveled by train through Europe. — often used before another noun ▪ a train [=railroad] station ▪ train tracks ▪ a train schedule/signal/ticket ▪ a train crash = (US) a train wreck 2 [count] old-fashioned : a group of people, vehicles, or animals that are moving in a line
▪ a funeral train ▪ a mule train — see also wagon train 3 [count] : an orderly series of events, actions, or ideas
▪ a train of events ▪ I lost my train of thought [=I forgot what I was thinking about] when you interrupted me. 4 [count] technical : a series of moving machine parts (such as gears) for controlling motion
▪ There's a problem with the car's drive train. ▪ the gear train 5 [count] : a part of a long dress that trails behind the woman who is wearing it
▪ the bride's train — see color picture
▪ a funeral train ▪ a mule train — see also wagon train
▪ a train of events ▪ I lost my train of thought [=I forgot what I was thinking about] when you interrupted me.
▪ There's a problem with the car's drive train. ▪ the gear train
▪ the bride's train — see color picture
in train
Brit, formal : in an active state or condition
▪ a process that had been in train for decades ▪ The plans have been set in train. [=set in motion]
▪ a process that had been in train for decades ▪ The plans have been set in train. [=set in motion]
— see also gravy train
