a train of thought

train of thought

One's uninterrupted progression of thinking. When the phone rang, it derailed my train of thought—I totally forget what I was talking about! Please don't interrupt my train of thought when I'm writing.
See also: of, thought, train

a train of ˈthought

the connected series of thoughts that are in your head at a particular time: The phone ringing interrupted my train of thought.
See also: of, thought, train