Ik Onkaar.
Three syllabules, 1. Ik 2. Oan 3. Kaar

Ik - lit. One

Oan/Ong = The Universe in its entirity

Kaar = in punjabi Kar means to do....Kaar is the one who does.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/jap-ji-sahib/1612-mool-mantar.html
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=1612

Ik Oankar = One Universe one who does
The one who 'does' ie creates preserves and destroyes the universe is Oankaar

The Ik denotes that He is one.

Ik Oankaar = One Universal Creator