Deemar
You are correct ~ as well.
There is no such thing as an 'Absolutely' Rigid Rotor but the phrase 'Rigid Rotor' was already taken.
The expression "'Absolutely' Rigid Rotor" is used in the context that 'absolute' is the optimal, albeit impossible, objective.
For more;
http://www.UniCopter.com/0815.html
Dave