Look up Ο, ο in Wiktionary, the free dictionary.

Greek alphabet
Αα Alpha	Νν Nu
Ββ Beta	Ξξ Xi
Γγ Gamma	Οο Omicron
Δδ Delta	Ππ Pi
Εε Epsilon	Ρρ Rho
Ζζ Zeta	Σσς Sigma
Ηη Eta	Ττ Tau
Θθ Theta	Υυ Upsilon
Ιι Iota	Φφ Phi
Κκ Kappa	Χχ Chi
Λλ Lambda	Ψψ Psi
Μμ Mu	Ωω Omega
Obsolete letters
Digamma	Qoppa
San	Sampi
Other characters
Stigma	Sho
Heta
Greek diacritics

Omicron or Omikron (uppercase Ο, lowercase ο, literally "small o" : Όμικρον, o mikron, micron meaning 'small' in contrast to omega) is the 15th letter of the Greek alphabet. In the system of Greek numerals it has a value of 70. It is rarely used in mathematics because it is indistinguishable from the Latin letter O and easily confused with the digit 0. This letter is equal to the Phoenician letter Ayin. In modern Greek, Omicron represents the sound IPA: [ɔː]. Letters that arose from omicron include Roman O and Cyrillic O.

In Unicode the capital letter is codepoint U+039F and the lowercase is U+03BF.

The upper-case letter of omicron (O) was originally used as a symbol for Big O notation, representing the asymptotic rate of growth of a function in mathematics.

This writing system-related article is a stub. You can help Wikipedia by expanding it.