Today’s word is: σκληρός (Gr. hard, indurated, harsh, dry)

Derivatives: 

sclerosis:

* pathological hardening of tissue; inability or reluctance to adapt. 

* Example: They are suffering from political sclerosis. 

sclerometer: 

* instrument used to measure the relative hardness of a material 

* Example: This tutorial shows you how to test the material using a sclerometer. * 

arteriosclerosis: 

* a chronic disease characterized by thickening and hardening of the arterial walls