We'd like to use analytics cookies to understand which symbols people look up, so we know what to research next. They are not used for advertising and we set none of them unless you say yes. What we store.
The twelfth Greek letter, and the SI prefix for one millionth.
Also known as: Greek letter mu, Mu symbol, Micro symbol, Micron sign, μ
Mu is the only Greek letter in this batch with a formally standardised meaning: as an SI prefix it means one millionth, as in the microgram and the micrometre. Everywhere else it is an ordinary variable name.
Is a letter of the Greek alphabet before it is a symbol: what it denotes is fixed by the field it appears in, not by the character itself. The uses below are the documented conventions, not competing definitions.
Contexts: Mathematics
In the SI system, denotes the prefix micro-, meaning one millionth — µg, µm, µs.
Contexts: Mathematics
In statistics, denotes the mean of a population, as against the sample mean.
Contexts: Mathematics
In mechanics, denotes the coefficient of friction between two surfaces.
Contexts: Mathematics
In electromagnetism, denotes magnetic permeability.
Contexts: Mathematics
In particle physics, denotes the muon, a heavier relative of the electron.
Contexts: Mathematics
Has a formally defined meaning as an SI prefix, which none of the other letters in this batch does — micro- is fixed by the International System of Units rather than by convention.
The SI defines the prefix, not the letter. Outside a unit, mu is an ordinary variable like any other.
Contexts: Mathematics
Exists in Unicode twice over: as the Greek letter and as a separate micro sign kept for compatibility with older encodings, which look alike but are distinct characters.
A practical trap for anyone searching or sorting text: two visually identical characters that do not match each other.
Contexts: Mathematics
A rounded u shape whose left stroke descends well below the writing line before ending.
The SI prefix micro has its own character, U+00B5, separate from this Greek letter at U+03BC. They render almost identically and are substituted for each other constantly.
Population mean and population standard deviation are the paired parameters of a normal distribution.