omicron
/əʊˈmaɪkrɒn/noun
1- the fifteenth letter of the Greek alphabet (O, o), transliterated as 'o'希腊字母表中第十五个字母（译写为o）。
1.1
Omicron
followed by Latin genitive Astronomy the fifteenth star in a constellation【天文】ο星（星座中第十五颗星）：Omicron Piscium.
双鱼座ο星。
词源
from Greek o mikron 'small o'.