An inversion is any
element of a
roller coaster that changes the train's
orientation so the riders are
upside down, even if only briefly. Common inversions include the
vertical loop,
corkscrew, and
cobra roll; less-common inversions include the
cutback,
heartline flip, and
Immelman.
The naming of inversions is actually a complex matter because various companies will assign different names to the same element. What Arrow Dynamics calls a boomerang is called a sidewinder by Vekoma; what Vekoma calls a boomerang is called a cobra roll by Intamin and Bolliger & Mabillard and a batwing by Arrow - B&M also has an element called the batwing, but it is not the same as Arrow's nor is it a cobra roll. Vekoma does have an element called the cobra roll, but it doesn't resemble a B&M cobra roll or an Arrow batwing! And so on.