refractory
/ɹɪˈfɹæk.təɹ.i/
noun
Meaning
A material or piece of material, such as a brick, that has a very high melting point.
adjective
Meaning
Obstinate and unruly; strongly opposed to something.
Not affected by great heat.
Difficult to treat.
Incapable of registering a reaction or stimulus.
Synonyms