Right now—with good reason—everyone is focused on Omicron as the name of the new COVID variant. But most people are unsure how to pronounce the word, or they (confidently) mispronounce it. And they also don’t know what it means.
I’m here to unpack all that. First of all, omicron is a letter of the Greek alphabet, for both ancient and modern Greek but with slightly differing pronunciations. In ancient Greek it represented the short “o” sound and was therefore pronounced /ˈɒmɪkrɒn/; the syllable boundary is difficult for English speakers, as it is o-micron, not omi-cron or om-icron. And thereby… aha!…you notice the suffix “micron,” meaning “small,” thus the short /o/ sound, contrasting with the “large” (long) “o,” which of course is o-mega—and another light bulb goes off: the last letter of the Greek alphabet, omega (ω or Ω). The long-short distinction has disappeared in modern Greek. In any case, the stress is on the first syllable: o′micron, with a short “i,” not omi′cron, with a long “i,” as too many people say, probably influenced by the word “micron.” And there’s no excuse whatsoever for saying “omni-cron,” as lots of politicians do, since it isn’t even a spelling pronunciation; it’s just a reflex from the common prefix “omni-.”
There’s still the question of whether you use a long or a short “o” at the beginning (when speaking English). When the variant was first announced, I used a short “o” because of my classical training through years and years of studying ancient Greek. But a fellow linguist convinced me that it is wrong to do so when speaking English: after all, we use a long “i” for π (pi) even though it’s pronounced just like the English letter “P” in both ancient and modern Greek, and we name all the other Greek letters as if they were English when that’s what we are speaking. What clinched it was the observation that we call the capital of France /’pærɪs/, not /pæ’ri/, which would sound terribly pretentious in English.
But wait! We’re not done. You also want to know what omicron means in mathematics. While I could explain its two uses in my own words, why should I when Tony Padilla does it so much better? One use is, fittingly, as an ancient Greek numeral; the other is as a symbol for the efficiency of an algorithm, as you will see in this video: