Definition of "mu"

Mu means "no thing." Like "Quality" it points outside the process of dualistic discrimination. Mu simply says, "No class; not one, not zero, not yes, not no." […] It's a great mistake, a kind of dishonesty, to sweep nature's mu answers under the carpet.

1974, Robert M[aynard] Pirsig, Zen and the Art of Motorcycle Maintenance: An Inquiry into Values, New York, N.Y.: William Morrow & Company

Achilles: Oh, but MU is Jōshū’s answer. By saying MU, Jōshū let the other monk know that only by not asking such questions can one know the answer to them.Tortoise: Jōshū “unasked” the question. […]Achilles: […] And the answer of “MU” here rejects the premises of the question, which are that one or the other must be chosen.

1979, Douglas Hofstadter, Gödel, Escher, Bach: An Eternal Golden Braid

"Mu," said Kelly Dahl.On one level mu means only yes, but on a deeper level of Zen it was often used by the master when the acolyte asked a stupid, unanswerable or wrongheaded question such as "Does a dog have the Buddha-nature?" The Master would answer only, "Mu," meaning—I say "yes" but mean "no," but the actual answer is: Unask the question.

1996, Dan Simmons, “Looking for Kelly Dahl”, in The Year's Best Science Fiction, page 424

The Fifth Patriarch's utterance You say mu [Buddha-nature] because Buddha-nature is emptiness articulates clearly and distinctly the truth that emptiness is not "no". In uttering Buddha-nature-emptiness one does not say "half a pound." One does not say "eight ounces." One says "mu."

2002, Norman Waddell, Masao Abe, The Heart of Dōgen's Shōbōgenzō, page 72

A monk once asked Master Joshu, 'Has a dog the Buddha Nature or not?' Joshu said, 'Mu!'

2010, Joan Price, Sacred Scriptures of the World Religions, page 70

That being the case, we should naturally choose to contemplate mu from morning to night, forgetting everything.

2012, Omori, Introduction To Zen Training, page 115

Consequently, though mu is mindlike, the likeness to individual consciousness cannot be pushed very far.

2012, Dr Robert Wilkinson, Nishida and Western Philosophy

The monk posed to Chaoi-chou a question: Does a dog have a buddha nature or not?" Chao-chou, without a moment's hesitation, answered, “Mu." (Translated as "No.")

2013, Sean Murphy, Natalie Goldberg, One Bird, One Stone: 108 Contemporary Zen Stories, page xvii

If mu is mind, consciousness, it is nothing.

2013, Maura O'Halloran, Pure Heart, Enlightened Mind

Pengyang county was administered by Guyuan before 1988. In contrast to Guyuan, Pengyang is relatively wealthy. Farmers earn a considerable income through tobacco cultivation, which can yield an annual gross income of Rmb 1,500-2,000 per mu. In 1996, the cultivated area of tobacco in Pengyang was 11,000 mu.⁷

2004, Peter Ho, “The Wasteland Auction Policy in Northwest China: Solving Environmental Degradation and Rural Poverty?”, in Rural Development in Transitional China: The New Agriculture‎, page 125‎

Of 114 village farming families, only ten had more than 30 mu of land and only five had more than 60 mu.

2007, Chang Liu, Peasants and Revolution in Rural China: Rural Political Change in the North China Plain and the Yangzi Delta, 1850-1949, page 87