a, o, f, g, n, h, r, t, i, u are letters that make 'train of thought'
thought, train, Tho, rain, thou, ain, though, in, AI, ai, RA, IN, Ra, Ho, In, Th are words within 'train of thought'
1 possible definitions for 'train of thought'
Under this definition, train of thought is a noun and has the following properties:
thread has the same meaning as train of thought
'train of thought' can be a type of thought process, thought, thinking, cerebration, intellection, mentation.
"I couldn't follow his train of thought", "he lost the thread of his argument"