upanayana उपनयन

Definition: n. that ceremony in which a Guru draws a boy towards himself and initiates him into one of the three twice-born classes (one of the twelve saṃskāra-s or purificatory rites [prescribed in the dharma-- sūtra-s and explained in the gṛhya-- sūtra-s] in which the boy is invested with the sacred thread [different for the three castes] and thus endowed with second or spiritual birth and qualified to learn the veda- by heart;a Brahman is initiated in the eighth year [or seventh according to hiraṇyakeśin-;or eighth from conception, according to śāṅkhāyana- etc.], a kṣatriya- in the eleventh, a vaiśya- in the twelfth;but the term could be delayed)

Dictionary: Monier-Williams
Literary Sources: