Synonyms for Zen (same or very similar meaning)
WordNet sense 1 (school of Mahayana Buddhism asserting that enlightenment can come through meditation and intuition rather than faith; China and Japan):
Zen BuddhismWordNet sense 2 (street name for lysergic acid diethylamide):
acid, dose, dot, pane, superman, battery-acid, Elvis, back breaker, loony toons, Lucy in the sky with diamondsFrom the ODE community, based on WordNetadd/edit