rigorous

the word 'rigorous' traces its lineage to the latin noun 'rigor', which signifies stiffness or numbness, derived from the verb 'rigere', meaning to be stiff. this physical sense of rigidity evolved metaphorically in medieval latin to describe harshness of climate or strictness of discipline. entering english via old french in the late middle ages, the adjective 'rigorous' came to characterize actions or standards performed with inflexible precision and thoroughness, mirroring the unyielding quality of its original meaning. the modern sense thus logically extends from a literal stiffness to a figurative strictness and exactitude.

Structure: rig (stiff) + or (noun suffix) + ous (adjective suffix) rig (from latin 'rigor', meaning stiffness, harshness, from the verb 'rigere', to be stiff); or (latin noun-forming suffix); ous (latin-derived adjective-forming suffix meaning 'full of' or 'characterized by').