To strive, to labour in difficulty, to fight (for or against), to contend.
To strive, or to make efforts, with a twisting, or with contortions of the body.
A contortion of the body in an attempt to escape or to perform a difficult task.
Strife, contention, great effort.
To weaken or work against; to hinder, sabotage.
To erode the base or foundation of something, e.g. by the action of water.
To dig underneath (something), to make a passage for destructive or military purposes; to sap.