unobtanium

Unobtainium is a fictional material used in science fiction to describe a substance with extraordinary properties that makes it highly desirable and nearly impossible to obtain. The specifics of unobtainium vary by work, but it is commonly portrayed as offering exceptional strength, lightness, energy density, superconductivity, or other technologically transformative traits, while remaining scarce or inaccessible.

The term blends the prefix un- with obtain and the conventional mineral suffix -ium, and it has become a catch-all label for materials that would dramatically change technology or economics if they existed. It originated in speculative fiction and has been used across books, films, and games as a storytelling device to justify cost, risk, or tradeoffs.

In popular culture, the most recognizable instance is James Cameron's Avatar, where unobtainium is a valuable mineral mined on Pandora to supply energy and industrial processes. In other narratives, unobtainium may simply be the unattainable prize that heroes chase, or a hyper-efficient material whose properties violate known physics. Because its properties are defined by the needs of the story, unobtainium acts as a flexible plot conceit rather than a real substance.

Outside fiction, unobtainium is sometimes used jokingly by engineers and technologists to refer to hypothetical materials with perfect or near-perfect properties, or as a placeholder name during design and discussion.