Waheguru is the word most used in Sikh naam simran, the remembrance of the divine name, repeated aloud in congregation, sung, and murmured silently with the breath. It is not, in origin, a proper name of God but an exclamation of wonder, wahe, an expression of awe, joined to guru, turned by devotional use into the name most characteristically on Sikh lips. Sikh teaching makes the disciplined remembrance of the name the heart of the spiritual path: it is through simran that the mind is turned from self-centredness (haumai) toward the divine.
The practice belongs to the wider North Indian devotional stream (bhakti and the sant tradition) that made the repetition of a divine name central, but Sikhism gave it a distinctive institutional shape, embedding it in daily prayer, in congregational singing (kirtan) of the scripture, and in the discipline of the initiated. To repeat Waheguru is understood not as a magical technique but as a training of attention and love, a keeping of God continually in mind through the ordinary activity of the day, the interior counterpart to the communal worship of the gurdwara.