an area of thick, hardened skin

accustom

to behave badly towards (a person); use, handle, (a machine, object) badly

treat badly or wrongly

(to cause a person, meat) to become tough

harden

a twisted or bent condition in a piece of wood etc caused by shrinking or expansion; (to cause something) to become bent or twisted from the usual or natural shape

bend, distort

bent or twisted

bend, distort