I'm on the train.

on Preposition

— positioned at the upper surface of, touching from above The apple is on the table. — at the date of Tim was born on the 4th of July. — along, forwards (continuing an action) drive on, rock on — about, dealing with the subject of I have a book on history. There was a World Summit on the Information Society a few weeks ago. — touching; hanging from I have no money on me at the moment. I would like to eat the fruit on the trees. — because of, due to He was arrested on suspicion of bribery. I contacted Joanne on a hunch that she would know about it. The stock price increased on news of a new product.

on Adjective

— If something is on, it is active, functioning or operating. The television is on. The lights are on, so it is very bright.

the Determiner

— Used, instead of a, to reference something specific, already known to exist. Compare "I read a book." and "I read the book." — Used with a stress, to show that the word following is special. Are you the John Smith that I went to school with? — Used with an adjective that acts like a noun to mean all of the people concerned The poor are always with us. — Used with superlatives forms of adjectives and adverbs. You are the best.

train Noun

— A long vehicle with many cars that are joined together. A train runs on a track. I took the train from Paris to Frankfurt.

train Verb

— If you train someone, you teach them a particular skill. In school we had computer training and sex education.