What is meant by transcendental meditation?

Broaden identity: Transcendental meditation (tm) seeks to expand the boundary of what one identifies as "the self." most people identify the boundary of the self as the body. Tm seeks, through meditation (sitting in the presence of a master without following a train of thoughts), to expand that boundary to include other people, nature, and eventually, the entire universe, achieving a state not describable in words.

Maharishi: Transcendental meditation (TM) is a form of meditation derived from yoga practice and popularized in the western world in the 1960s and 1970s by Maharishi Mahesh Yogi. The Maharishi was the Beatles' guru for a time. Their song "Sexy Sadie" was originally titled "Maharishi." It was written after they had become somewhat disillusioned with him.