The term for God in Sikhism is "Waheguru". Guru Nanak describes God as "nirankar" (from the Sanskrit "nirākārā", meaning "formless"), "akal" (meaning "eternal") and "alakh" (from the Sanskrit "alakśya", meaning "invisible" or "unobserved"). Sikhism's principal scripture, the Guru Granth Sahib, starts with the figure "1", signifying the unity of God. Nanak's interpretation of God is that of a single, personal and transcendental creator with whom the devotee must develop a most intimate faith and relationship to achieve salvation. Sikhism advocates the belief in one god who is omnipresent ("sarav vi'āpak"), whose qualities are infinite and who is without gender, a nature represented (especially in the Guru Granth Sahib) by the term "Ek Onkar".