A non-biologically related look-alike or double of a living person.

Origin: The word 'doppelgänger' is derived from the German language, where 'doppel' means 'double' and 'gänger' means 'walker' or 'goer'. It first appeared in German literature in the late 18th century, combining 'doppel' from Middle High German 'doppel' (double) and 'gänger' from Middle High German 'ganger' (walker). Historical and Cultural Context: The concept of a doppelgänger has been present in folklore and mythology across different cultures, but it was first popularized in German Romantic literature. It was used to describe an apparition or double of a living person that is often considered a harbinger of bad luck. The term was first attested in the novel 'Siegfried the Mystic' by Jean Paul in 1796. Evolution: Over time, the term 'doppelgänger' has been borrowed into English, retaining its original meaning. Its usage expanded to describe any look-alike or double, not necessarily ominous. It has cognates in other languages, such as the French 'sosie' and the Spanish 'doble'. Modern Relevance: Today, 'doppelgänger' is commonly used in English to describe someone who looks like someone else, often used in a humorous context. It is also used in pop culture, particularly in films and literature, to explore themes of identity and duality.

There's a viral internet challenge called the 'Doppelgänger Challenge,' where people try to find strangers who look just like them.