omicron

Meanings

1. The 15th letter of the Classical and Modern Greek alphabets (16th in Ancient and Old Greek), used in ordering lists as in naming (astronomy) the 15th star of a constellation or (epidemiology) the 15th discovered major variant of a disease.

1. Ellipsis of Omicron variant.

1. Ellipsis of Omicron variant.

1. Alternative form of omicron (Greek letter) (especially in the majuscule form)

1. Ellipsis of Omicron Hill: a mountain in North Slope borough, Alaska, United States.

Etymology

From Latin omicron, from Koine Greek ὂ μῑκρόν (ò mīkrón, “little o”), named in contrast with omega (“big o”). The uncommon form omicra is similarly borrowed from Latin and Greek. The use for designating stars in a constellation—typically in order of apparent brightness—began with Johann Bayer's 1603 Uranometria.