Transcendental Meditation, the technique taught from the 1950s by Maharishi Mahesh Yogi, assigns each practitioner a mantra at a paid initiation and instructs that it not be revealed to anyone. The movement presents the mantra as selected for the individual; lists purporting to reproduce the assignment scheme have circulated, but this reference work does not reproduce them, both out of respect for a living organisation's stated practice and because the content is beside the point at issue.
What can be described, and is a matter of public record, is the institution and its history. In the United States the courts examined TM directly: in Malnak v. Yogi the technique's teaching in public schools was found to be religious in nature for constitutional purposes, despite the movement's presentation of it as a secular science of consciousness. Scholars of new religious movements have traced how a mantra practice drawn from Hindu devotional roots was repackaged for a Western market as a stress-reduction method. The secrecy and the fee are, in this case, part of what a neutral account should record, not the syllable itself.