Omicron


Omicron is the 15th letter of the Greek alphabet. In the system of Greek numerals it has a value of 70. This letter is derived from the Phoenician letter ayin. In classical Greek, omicron represented the sound in contrast to omega and ου. In modern Greek, omicron represents the mid back rounded vowel, the same sound as omega. Letters that arose from omicron include Roman O and Cyrillic O.
The upper-case letter of omicron was originally used in mathematics as a symbol for Big O notation, but has fallen out of favor because omicron is indistinguishable from the Latin letter O and easily confused with the digit zero.
Omicron is used to designate the fifteenth star in a constellation group, its ordinal placement a function of both magnitude and position. Such stars include Omicron Andromedae, Omicron Ceti, and Omicron Persei.

Character encodings

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.