Omicron: What It Is, Exactly

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omicronŏm′ĭ-krŏn″, ō′mĭ-

noun

1. The 15th letter of the Greek alphabet.
2. The fifteenth letter of the Greek alphaoet (O, o).
3. Lit., the little, or short, O, o; the fifteenth letter of the Greek alphabet.
4. the name for the 15th letter of Classical and Modern Greek. The 16th in Ancient and Old Greek.
5. the 15th letter of the Greek alphabet