adj. - Something stupefying, generally used in a positive fashion. Used to denote a level of something so enormous, it's ridiculous almost to the point of being stupid.
Also used as an adv., it is less ubiquitously positive when found in this form.
You check that cat on the sax? He's so good it's stupidacious!
A Shackteau is a humble, weather-beaten, structurally questionable shelter located in a spectacular or highly coveted place—Wales, Jackson Hole, Sun Valley, Crested Butte, coastal Maine, the Alps—where the building itself may be worth almost nothing, but the dirt, view, access, and mythology make it absurdly valuable.
In use:
Shackteâu - We thought it was an abandoned shed until the realtor called it a rare alpine Shackteâu with unobstructed views and listed it for $2million.