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slang Any material that is fictional, hypothetical, impossible to find, extremely rare, prohibitively costly, or no longer available. A portmanteau of the terms "unobtainable" and "titanium" (sometimes spelled "unobtanium" based on the latter). Looking at the issue from a purely mathematical standpoint, yes, it should be possible to lift something that heavy up to the top of the tower. But the mechanisms to actually perform such a lift would have to be made of unobtainium to withstand such immense forces. Scientists warn that the continued manufacture of electronics could turn the rare-earth metal into unobtanium.
n. something highly desirable that cannot be found; a fantastic, perfect metallic substance. (see also obtanium.) Of course, his bike is made of unobtanium and should stand up in a volcanic eruption.