Yahwehism Adherents to Hebrew Bible / Mosaic law; Sabbath keeping, diet, festivals, sacred name.
YHWH ("Yahweh") The 'Tetragrammaton' in the Tanach, the sacred name of God meaning 'I am.' It is so holy that it was never uttered and 'adonai' (LORD) was substituted.
Yin / Yang Polarity of reality in Chinese philosophy: Yang is masculine, dynamic, bright, and good.; Yin is feminine, passive, dark, and bad; produce the elements and the cycle of seasons.
Yoga Discipline designed to induce union with Brahma.
Yogi Hindu holy man who has reached enlightenment through Yogic practices.
Yom Kippur ('Day of Atonement') Jewish day of fasting and repentance.
Yugas ('ages') Hindu view of eternity as constant cycle of creation, maintenance and devolution;