Bimoment (aka warping moment) is a term used in the analysis of beams (continuum mechanics), which relates to torsion and warping. Its symbol is Mω.

Bimoment distribution method for thin-walled beams
Bimoment equilibrium of finite segments of Hillerborg plate
Bimoment contribution to stability of thin-walled assemblages
Warping and bimoment transmission through diagonally stiffened beam-to-column joints
Warping and bimoment transmission through diagonally stiffened beam-to-column joints
Twist Control of an I-beam Through Vlasov Bimoment Actuation
Influence of bimoment on the torsional and flexural–torsional elastic stability of thin-walled beams
THE METHOD OF BIMOMENT DISTRIBUTION FOR THE ANALYSIS OF CONTINUOUS THIN-WALLED STRUCTURES SUBJECT TO TORSION
THE METHOD OF BIMOMENT DISTRIBUTION FOR THE ANALYSIS OF CONTINUOUS THIN-WALLED STRUCTURES SUBJECT TO TORSION
On Solution of the Problem of Bending of Orthotropic Plates on the Basis of Bimoment Theory