Omicron

Omicron (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 letters O, o and easily confused with the digit 0. This letter is derived from the Phoenician letter ayin . In classical Greek, omicron represented the sound [o] in contrast to omega [ɔː] and ου [oː]. In modern Greek, omicron represents the sound [ɔ]. 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 in mathematics as a symbol for Big O notation, representing the asymptotic rate of growth of a function.

Character encodings

• Greek Omicron / Coptic O
Character Ο ο
Unicode name GREEK CAPITAL LETTER OMICRON GREEK SMALL LETTER OMICRON COPTIC CAPITAL LETTER O COPTIC SMALL LETTER O
Encodings decimal hex decimal hex decimal hex decimal hex
Unicode 927 U+039F 959 U+03BF 11422 U+2C9E 11423 U+2C9F
UTF-8 206 159 CE 9F 206 191 CE BF 226 178 158 E2 B2 9E 226 178 159 E2 B2 9F
Numeric character reference &#927; &#x39F; &#959; &#x3BF; &#11422; &#x2C9E; &#11423; &#x2C9F;
Named character reference &Omicron; &omicron;
DOS Greek 142 8E 166 A6
DOS Greek-2 190 BE 233 E9
Windows 1253 207 CF 239 EF

Source:[2]

• Mathematical Omicron
Character 𝚶 𝛐 𝛰 𝜊 𝜪 𝝄
Unicode name MATHEMATICAL BOLD
CAPITAL OMICRON
MATHEMATICAL BOLD
SMALL OMICRON
MATHEMATICAL ITALIC
CAPITAL OMICRON
MATHEMATICAL ITALIC
SMALL OMICRON
MATHEMATICAL BOLD ITALIC
CAPITAL OMICRON
MATHEMATICAL BOLD ITALIC
SMALL OMICRON
Encodings decimal hex decimal hex decimal hex decimal hex decimal hex decimal hex
Unicode 120502 U+1D6B6 120528 U+1D6D0 120560 U+1D6F0 120586 U+1D70A 120618 U+1D72A 120644 U+1D744
UTF-8 240 157 154 182 F0 9D 9A B6 240 157 155 144 F0 9D 9B 90 240 157 155 176 F0 9D 9B B0 240 157 156 138 F0 9D 9C 8A 240 157 156 170 F0 9D 9C AA 240 157 157 132 F0 9D 9D 84
UTF-16 55349 57014 D835 DEB6 55349 57040 D835 DED0 55349 57072 D835 DEF0 55349 57098 D835 DF0A 55349 57130 D835 DF2A 55349 57156 D835 DF44
Numeric character reference &#120502; &#x1D6B6; &#120528; &#x1D6D0; &#120560; &#x1D6F0; &#120586; &#x1D70A; &#120618; &#x1D72A; &#120644; &#x1D744;
Character 𝝤 𝝾 𝞞 𝞸
Unicode name MATHEMATICAL SANS-SERIF
BOLD CAPITAL OMICRON
MATHEMATICAL SANS-SERIF
BOLD SMALL OMICRON
MATHEMATICAL SANS-SERIF
BOLD ITALIC CAPITAL OMICRON
MATHEMATICAL SANS-SERIF
BOLD ITALIC SMALL OMICRON
Encodings decimal hex decimal hex decimal hex decimal hex
Unicode 120676 U+1D764 120702 U+1D77E 120734 U+1D79E 120760 U+1D7B8
UTF-8 240 157 157 164 F0 9D 9D A4 240 157 157 190 F0 9D 9D BE 240 157 158 158 F0 9D 9E 9E 240 157 158 184 F0 9D 9E B8
UTF-16 55349 57188 D835 DF64 55349 57214 D835 DF7E 55349 57246 D835 DF9E 55349 57272 D835 DFB8
Numeric character reference &#120676; &#x1D764; &#120702; &#x1D77E; &#120734; &#x1D79E; &#120760; &#x1D7B8;

These characters are used only as mathematical symbols. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style.