I think the original definition of "rigidity" referred to the presence or absence of hinges.
Fully articulated = flap and lead/lag hinges
Semi-rigid (semi-articluated) = flap hinge(s) only (UH-1, R-22)
Rigid = no hinges
The use of these terms became somewhat ambiguous with the advent of flexible blade elements and/or elastomeric bearings.
A rigid rotor may be hingeless, but still have bearings, e.g. Bo105 and Lynx for blade feathering.
A hingeless and bearingless rotor, e.g. EC135, may not be "rigid" at all, as the blade root is is highly flexible in bending (for flapping) and torsion (for feathering)
To add even more confusion, there are quite a lot of fully articluated rotors that have no hinges. Here, the function of hinges (elimination bending moments between the blade and the rotor head) is taken over by elastomeric bearings.
BTW, manufacturer's manuals are not fully reliable, neither is my website
Burkhard,
www.b-domke.de/AviationImages/Rotorhead.html