The Omikron (Greek neuter Όμικρον, " little O ", spoke briefly, [see also Omega ]; Ο majuscule, minuscule ο ) is the 15th letter of the Greek alphabet and has among the ancient Greeks after the Milesian principle a numerical value of 70.
The sign comes from the Phoenician consonants Ayin, which the Greeks the vowel is " o" tasks. It is one of the few letters, in which the Greeks took over the Semitic letter names. Later, the Greeks expanded their alphabet by several additional letters, one of which Omega (Greek: big O) was last. From the Omikron the Latin O, which then fell away, the Greek letter name evolved over the Etruscan script.
In mathematics, a large Omikron by Paul Bachmann in 1892 used to describe the magnitude of a function. Today this notation is known as the Landau symbol and is usually understood as Latin O.