Sikhism took the opposite approach to the very problem the guru relationship exposes elsewhere. After a line of ten human Gurus beginning with Guru Nanak in the late fifteenth century, the tenth, Guru Gobind Singh, declared before his death in 1708 that the succession of living Gurus was closed and that the scripture, the Guru Granth Sahib, would be the eternal Guru of the Sikh community from then on, replacing personal succession with the authority of a fixed text no individual could claim to embody or amend. That closure is a deliberate doctrinal solution to the accountability problem inherent in a living guru, since a book cannot demand secrecy, cannot abuse a disciple, and cannot be flattered into unchecked authority the way a living teacher can.
Outside these traditions, the word has drifted a long way from any of its religious senses. English borrowed guru in the twentieth century as a casual label for any recognised expert, a business guru, a tech guru, a fitness guru, stripping the word of the ideas of initiation, lineage and spiritual authority that give the religious title its actual weight, so that the same syllables now describe both a master within an unbroken chain of transmission and a management consultant with a bestselling book.