# Greek letters used in mathematics, science, and engineering

Greek letters are used in mathematics, science, engineering, and other areas where mathematical notation is used as symbols for constants, special functions, and also conventionally for variables representing certain quantities. In these contexts, the capital letters and the small letters represent distinct and unrelated entities. Those Greek letters which have the same form as Latin letters are usually not used: capital A, B, E, H, I, K, M, N, O, P, T, X, Y, Z. Small ι (iota), ο (omicron) and υ (upsilon) are also rarely used, since they closely resemble the Latin letters i, o and u. Sometimes font variants of Greek letters are used as distinct symbols in mathematics, in particular for φ (phi) and π (pi).

In mathematical finance, the Greeks are the variables denoted by Greek letters used to describe the risk of certain investments.

The majority of English-speaking mathematicians use neither the modern nor the historical Greek pronunciations of the names of the letters, but the traditional English pronunciation, e.g. for θ, cf. ancient [tʰɛ̂ːta] and modern [ˈθita].

## Typography

The Greek letter forms used in mathematics are often different from those used in Greek-language text: they are designed to be used in isolation, not connected to other letters, and some use variant forms which are not normally used in current Greek typography.

The OpenType font format has the feature tag 'mgrk' "Mathematical Greek" to identify a glyph as representing a Greek letter to be used in mathematical (as opposed to Greek language) contexts.

The table below shows a comparison of Greek letters rendered in TeX and HTML. The font used in the TeX rendering is an italic style. This is in line with the convention that variables should be italicized. As Greek letters are more often than not used as variables in mathematical formulas, a Greek letter appearing similar to the TeX rendering is more likely to be encountered in works involving mathematics.

Greek letters
Name TeX HTML Name TeX HTML Name TeX HTML Name TeX HTML Name TeX HTML
Alpha $\Alpha \, \alpha \,$ Α α Digamma $\digamma \,$ Ϝ ϝ Kappa $\Kappa \, \kappa \, \varkappa \,$ Κ κ ϰ Omicron $\Omicron \, \omicron \,$ Ο ο Upsilon $\Upsilon \, \upsilon \,$ Υ υ
Beta $\Beta \, \beta \,$ Β β Zeta $\Zeta \, \zeta \,$ Ζ ζ Lambda $\Lambda \, \lambda \,$ Λ λ Pi $\Pi \, \pi \, \varpi \,$ Π π ϖ Phi $\Phi \, \phi \, \varphi \,$ Φ ϕ φ
Gamma $\Gamma \, \gamma \,$ Γ γ Eta $\Eta \, \eta \,$ Η η Mu $\Mu \, \mu \,$ Μ μ Rho $\Rho \, \rho \, \varrho \,$ Ρ ρ ϱ Chi $\Chi \, \chi \,$ Χ χ
Delta $\Delta \, \delta \,$ Δ δ Theta $\Theta \, \theta \, \vartheta \,$ Θ θ ϑ Nu $\Nu \, \nu \,$ Ν ν Sigma $\Sigma \, \sigma \, \varsigma \,$ Σ σ ς Psi $\Psi \, \psi \,$ Ψ ψ
Epsilon $\Epsilon \, \epsilon \, \varepsilon \,$ Ε ϵ ε Iota $\Iota \, \iota \,$ Ι ι Xi $\Xi \, \xi \,$ Ξ ξ Tau $\Tau \, \tau \,$ Τ τ Omega $\Omega \, \omega \,$ Ω ω

## Concepts represented by a Greek letter

### Ϝϝ (digamma)

• Ϝ is sometimes used to represent the digamma function, though the Latin letter F (which is nearly identical) is usually substituted.

### Οο (omicron)

• Ο represents:
• o represents:

### Ρρ (rho)

• Ρ represents:
• one of the Gegenbauer functions in analytic number theory.

### Υυ (upsilon)

• Υ represents:
• an elementary particle
• υ represents: