Epsilon, the fifth letter of the Greek alphabet is the next in line in our series of articles on Greek letter. Without further ado, here is everything you need to know about Epsilon symbol, its history and origins, meanings and uses in science and math.

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**The Greek Epsilon Symbol and Its Origins**

Epsilon (uppercase Ε, lowercase ε or lunate ϵ; Greek: έψιλον) is the fifth letter of the Greek alphabet. Just like other Greek alphabet letters, it also represents a value in the Greek numeral system. It has a value of 5.

The Greek Epsilon symbol is believed to have been adopted from the Phoenician letter He.

Meanwhile, letters that have subsequently been derived from the Greek Epsilon include the Cyrillic Е, È, Ё, Є and Э. The Roman letter E, as well as Ë and Ɛ are also believed to be of Greek origin.

Essentially, the uppercase or capital Epsilon sign is identical to the Latin letter E, which many people all over the globe use in their alphabets.

The lowercase Epsilon letter comes with two typographical variants, although both were derived from medieval Greek handwriting.

One version is the most common in modern Greek typography. It looks like a reversed number 3.

The other version is known as the lunate Epsilon. It looks like a semi-circle with a horizontal bar going across it.

There is also another Latin Epsilon, known as the “open e”. This open e is used as an IPA phonetic symbol. This version is thought to be the basis for the euro sign.

All in all, this Greek alphabet letter has at least six archaic local variants.

**Epsilon Symbol – How is It Used Today**

As with the rest of the Greek alphabet, Epsilon is used to symbolize and represent a number of concepts, measurements, constants, and values. However, the capital Epsilon letter is not as widely used as its lowercase counterpart (and its variants), because of its resemblance with the Latin letter E.

Let’s take a closer look at how the Epsilon symbol is used to denote various things.

In mathematics, specifically calculus, the Epsilon symbol is used to denote a random and small positive quantity in terms of the definition of limit. Also in math, David Hilbert utilized Epsilon terms to serve as an extension to first-order predicate calculus (first-order logic).

In statistics, Epsilon is used to denote error terms, as well as the degree of sphericity in repeated measures ANOVAs (analysis of variance).

The Epsilon symbol is also used to denote the Levi-Civita symbol, as well as to represent dual numbers. The Epsilon sign is also sometimes used to represent the Heaviside step function, which was named after Oliver Heaviside.

On the other hand, in set theory, the Epsilon symbol signifies the epsilon numbers, which are ordinal numbers that meet a fixed point.

In computer science, the term Epsilon was used in machine epsilon, which gives an upper bound on relative error.

In physics, the Epsilon symbol denotes the permittivity of a medium. When used with subscript 0, it denotes the permittivity of free space.

Also in physics, Epsilon can indicate a material’s strain.

The Epsilon sign is also used in astronomy. For one, it represents the fifth brightest star in a particular constellation. It also denotes axial tilt in planetary science.

The term Epsilon was also used to name Uranus’ farthest and most visible ring.

In chemistry, the Greek letter represents a chromophore’s molar extinction coefficient. Meanwhile, in economics, the lowercase Epsilon refers to elasticity.

In agronomy, Epsilon represents a plant or crop’s photosynthetic efficiency.

**How to Type the Epsilon Symbol**

There are several uses for the Epsilon sign, particularly its lowercase symbol. As such, it shouldn’t come as a surprise that you may find yourself looking for ways on how to type or insert the symbol into documents.

Fortunately, there are a few ways to type and insert Greek alphabet letters like Epsilon even if you’re using an English keyboard. Check out the steps below to easily add Epsilon in your document.

**How to Type the Epsilon Symbol in Word**

If you need to type the Greek alphabet letter Epsilon sign in a Word document, you can do so by following a few steps.

**Method 1: Using the ALT keyboard shortcut**

If you’re using a full keyboard, which is a keyboard that has a full numeric keypad, you can use ALT-code shortcuts to type Epsilon. Basically, you’ll have to press and hold the ALT key while you type these codes on the numeric keypad:

- 238 for the lowercase Epsilon
- 941 for the lowercase Epsilon with Tonos
- 1013 for the lunate Epsilon
- 1014 for the reversed lunate Epsilon
- 917 for the uppercase Epsilon
- 904 for the uppercase Epsilon with Tonos

**Method 2: Using the Insert > Equation method**

Step 1: Locate the Insert tab on the functions menu in Word.

Step 2: Click on Equation.

Step 3: Choose the specific Epsilon symbol you need to insert. Click on it.

Step 4: Press Enter to finish adding the symbol into the document.

**Method 3: Using the Insert > Symbol method**

Step 1: Locate the Insert tab on the functions menu in Word.

Step 2: Click on Symbols, then More Symbols.

Step 3: On the dialog box, choose “Greek and Coptic” on the Subset field.

Step 4: A selection of symbols will be shown. Look for the specific Epsilon symbol you need to add to your document.

Step 5: Click Insert, then close the dialog box.

**How to Insert the Epsilon Symbol in Excel**

Should you need to add or insert the Epsilon letter into an Excel file, you can also follow the two methods under the Insert function.

Simply locate the Insert tab from the functions menu in your Excel window. Then, insert the Epsilon sign either as an Equation or as a Symbol.

Another way to add Epsilon symbols into an Excel file is to copy-paste it.

**How to Type the Epsilon Symbol on Mac**

Typing the Epsilon sign on a Mac is as easy as adding other letters of the Greek alphabet. All you have to do is press and hold the CTRL key, press G, and then E.

The step above will give you a lowercase Epsilon. If you need the uppercase symbol, simply hit CAPS LOCK before typing the shortcut.