der Zwilling
twin
One of two children who were born in the same birth.
Meine Schwester ist mein Zwilling, aber wir sehen uns überhaupt nicht ähnlich.
My sister is my twin, but we don't look alike at all.

twin
Loading your saved state.
twin
One of two children who were born in the same birth.
Meine Schwester ist mein Zwilling, aber wir sehen uns überhaupt nicht ähnlich.
My sister is my twin, but we don't look alike at all.

The word 'Zwilling' (twin) is derived from the number 'zwei' (two). The ending '-ling' is often used to refer to a person characterized by the root word—here, a person who belongs to a pair of two.
Die beiden sehen sich so ähnlich, sie müssen Zwillinge sein.
The two look so alike; they must be twins.
In a biological context, a distinction is made between 'eineiige Zwillinge' (identical twins, who look very similar) and 'zweieiige Zwillinge' (fraternal twins, who may look like regular siblings).
Obwohl sie eineiige Zwillinge sind, haben sie sehr unterschiedliche Persönlichkeiten.
Although they are identical twins, they have very different personalities.
When 'Zwilling' is used in the context of horoscopes, zodiac signs, or birthdays, it refers to the zodiac sign Gemini (May 21 to June 21). The plural 'Zwillinge' is also often used for the zodiac sign.
Mein Bruder ist im Sternzeichen Zwillinge geboren.
My brother was born under the sign of Gemini.
This meaning is colloquial and is often used slightly ironically. A typical expression is 'optischer Zwilling' (visual twin) to describe a striking resemblance between two people.
Der Schauspieler ist der optische Zwilling meines Bruders.
The actor is my brother's visual twin.
clone
'der Zwilling' and 'der Klon' can both have to do with strong similarity. A 'Zwilling' is normally one of two children born in the same birth. Colloquially, you can also say that someone or something is like a 'Zwilling' if it looks almost identical. A 'Klon', by contrast, is a genetically identical copy of a living organism or an exact copy of a product. The words can be confused because both can describe very similar people or things. In everyday life, you say 'Zwilling' for siblings; in science, technology, or for exact copies, 'Klon' is more likely.

Im Zug saß ich neben einem Zwilling, der seinem Bruder sehr ähnlich sah.
On the train, I sat next to a twin who looked very much like his brother.
Das neue Handy wirkt wie ein Klon eines bekannten Modells.
The new phone looks like a clone of a well-known model.