U03BC

U+03BC, often written as U03BC, is the Unicode code point for the Greek small letter mu. It represents the lowercase form of the Greek letter mu and is located in the Greek and Coptic block. The official Unicode name is GREEK SMALL LETTER MU, and its uppercase counterpart is U+039C, GREEK CAPITAL LETTER MU. The character has the general category of a lowercase letter (Ll) and has historical value in Greek numerals, where it represents the number 40.

In the Greek language, mu is used as a standard letter in writing and phonology, corresponding to the sound /m/. It appears in words across ancient and modern Greek and is transliterated as "m" in romanization. Beyond linguistic use, mu has become a widely adopted symbol in mathematics, science, and engineering. It is commonly used to denote the population mean in statistics, the coefficient of friction in physics, dynamic viscosity in fluid mechanics, chemical potential, and various other physical quantities. In SI units, the micro- prefix is represented by the Greek mu (μ), though the actual micro sign (µ, U+00B5) is a distinct code point and can be used in some fonts and fonts rendering inconsistencies.

Typography and encoding notes: the Greek small letter mu should be encoded as U+03BC to correctly reflect its Greek origin. In HTML, it can be written as μ or μ in most fonts. The glyph μ is visually distinct from the micro sign µ, which can look similar but has a different code point and usage.

Origin and history: mu originated from the Phoenician letter mem and was adopted into the Greek alphabet, where it received its current forms and phonetic value. It remains a common symbol across disciplines and languages.