Ek Onkar (also ੴ, ਇਕ ਓਅੰਕਾਰ, Ik Ōaṅkār, Ek Omkar, Ik Omkar and other variants) means one God and is a central tenet of Sikh religious philosophy. It is also a symbol of the unity of God in Sikhism, and is commonly found on Gurdwaras. Guru Nanak, the founder of the Sikh religion, used the Hindu Vedantic idea of Om: the most sacred syllable in Hinduism. Ek Onkar is a combination of three letters: Ek - one, Om - the sacred letter for God, and the kar - which is a line drawn over the Om, signifying the continuity, timelessness and eternal presence of Om (God).

Ek means "one" (Sanskrit eka).

Onkar came from Sanskrit Omkāra, which means "he or it which makes Om".

Ek Onkar is the first phrase in the Mool Mantra:

One Universal Creator God. The Name Is Truth. Creative Being Personified. No Fear. No Hatred. Image Of The Undying, Beyond Birth, Self-Existent. By Guru's Grace. True In The Primal Beginning. True Throughout The Ages. True Here And Now. O Nanak, Forever And Ever True.

An alternative interpretation:

• Ik - means One
• Oan - The Creator
• Kaa - The Sustainer
• Aar - The Destroyer

David C. Lane makes reference

References

1.   Late Baba Thakar Singh of Damdami Taksal, Amritsar
2.