Original: Omicron ( uppercase Î , lowercase Î , literally '' small o '' : Î Î 1\/4 Î Î Ï Î Î 1\/2 , o mikron , micron meaning ` small ' in contrast to omega ) is the 15th letter of the Greek alphabet .
Simplified: Omicron ( uppercase\/lowercase Î Î ) , is the letter of the Greek alphabet , used to represent the '' o '' sound in Ancient and Modern Greek .