Waheguru (Punjabi: vāhigurū) is a Gurmantar (meditating mantra) in Sikhism, to connect with the Supreme Being or the creator of all. Waheguru means Wondrous Enlightener (beyond explanation) who eliminates the darkness of our mind with the light of his divine light. It also denotes the concept of oneness of God. "Wahed" in Arabic means "one and only". Here the word "WAHE" means wonderful which can`t be explained, "GU" means darkness and "RU" means divine light of knowledge. Sikh`s Guru gave this mantra. Sikh`s Guru gave this mantra by combining mantras of all four ages as: "Waawa" represents Vasdev, "Hahha" represents Hari, "Gagga" represents Gobind and "Rarra" represents Ram (Vaars of Bhai Gurdas ji). Waheguru is a mantra(tool) to connect with divine by chanting with love and mental concentration in rhythm which generates distinct flow of the specific currents of the sound, those sound vibrations hit our central nervous system and our endocrine glands secretes the chemical called as “Amrit Rass”(Ambrosial nectar) as per Gurbani.
The most common usage of the word "Waheguru" is in the greeting Sikhs use with each other:
"Waheguru" (Vaheguru) and its variant "Vahiguru" appear 16 times in Guru Granth Sahib. Vahiguru occurs on Ang 188, on Ang 1403 and once on Ang 1404. Other words used in the Guru Granth Sahib to refer to God are: Akaal Purakh ( the timeless being which never dies, Ik Onkar ( God is One), Satguru ("true teacher"), Satnaam ("true name"), Rama, Rahman, Purushah, Allah, and Khuda among others.
Guru Gobind Singh, the tenth Guru of the Sikhs (1666–1708), used "Waheguru" in the invocatory formula ("Ik Onkar Sri Waheguru ji ki Fateh", besides the traditional "Ik Onkar Satguru Prasada") at the beginning of some of his compositions as well as in the Sikh salutation ("Waheguru ji ka Khalsa Waheguru ji ki Fateh"). Bhai Gurdas at one place in his Varan (I.49) construes "vahiguru" as an acrostic using the first consonants of the names of four divine incarnations of the Hindu tradition appearing in four successive eons. Modern scholars, however, affirm that the name Vahiguru is owed originally to the Gurus, most likely to the founder of the faith, Guru Nanak, himself. According to this view, Vahiguru is a compound of two words, one from Persian and the other from Sanskrit, joined in a symbiotic relationship to define the indefinable indescribable Ultimate Reality. "Vah" in Persian is an interjection of wonder and admiration, and "guru" (Sanskrit guru: "heavy, weighty, great, venerable; a spiritual parent or preceptor") has been frequently used by Guru Nanak and his successors for "SATGURU "(True Guru) or God. Bhai Santokh Singh, in Sri Guru Nanak Prakash (pp. 1249–51), reporting Guru Nanak’s testament to the Sikhs has thus explicated "Vahiguru": "Vah" is wonder at the Divine might; while guru means a spiritual and devotional teacher.