I have been reading an abridged version of 《西游记》and in the book it talks about 跟头云which translates as cloud somersaulting...

Now when I look this up in a dictionary i can't find it but I do find 筋斗云。This does not seem to have the meaning of cloud travelling or somersault or anything. 

does anyone know what the right name for the being able to travel 108000 miles with the clouds is?