Our word "doppelganger" comes from German. It literally means "double-goer." In German, and in English, too, a doppelganger is a ghost that looks just like some living person. Oooh, spooky! That makes for a good ghost story, right? About a ghost out there, wandering around, looking just like you? That's your doppelganger.
But more loosely, a doppelganger is a copy of someone or something, or a very similar version of it that seems creepy or ghostly.
If you see someone who looks just like you, you might say, "I saw my doppelganger today."
In the show Sister, Sister, Tia and Tamera are strangers. When they see each other for the first time, each girl thinks she's looking at her doppelganger. "That girl has my face!" they shout. But, they actually really are twins. They were just raised in separate homes since they were babies.
You might wonder, what's the difference between twins and doppelgangers? Well, twins are siblings! They belong to the same family. They look alike because they share DNA. But doppelgangers are not related. They look alike from sheer coincidence.
Here's me on the left, and an actress named Maria on the right. Do you think I'm Maria's doppelganger?
As you can see, we use the word "doppelganger" to joke around and talk about how one thing or person really looks like another. Like this: "Hey Justin, I found your doppelganger! He has spaghetti hair, too!"