refractory

Etymology

From Latin refractārius (“obstinate”), from refractus, past participle of refringere (“to break up”). Originally refractary, refractarie, but reanalysed after other adjectives in -ory.

adj

1. Obstinate and unruly; strongly opposed to something.
   […] in most instances attempts to coerce the refractory and disobedient have been the signals of bloody wars, […] 1787, Alexander Hamilton, “No. 16”, in The Federalist, published 1863, page 103
2. Not affected by great heat.
   Pure lime is extremely refractory, but readily fusible if any silex is brought in contact with it; […] 1855, Frederick Overman, A Treatise on Metallurgy, page 315
3. (medicine) Difficult to treat.
   Many of the vague and refractory cases of neck and shoulder pain and of migraine may be due to cervical disc disease. 1949, Albert Fields, John Hoesley, “Neck and Shoulder Pain”, in Calif. Med., 70(6):478-482
   In 33 adult patients with long standing refractory epilepsy on treatment with one or two standard anti-convulsant drugs, 1990, H. A. Ring et al., “Vigabatrin: rational treatment for chronic epilepsy”, in J. Neurol. Neurosurg.Psychiatry, 53(12):1051-1055
4. (biology) Incapable of registering a reaction or stimulus.
   The production of a generator potential leaves a refractory state in the receptor membrane […] 1959, Nobusada Ishiko, Werner R. Loewenstein, “Electrical output of a receptor membrane”, in Science, 130:1405-6
   The […] delivery of external stimuli […] delineates the pacemaker refractory period after the emission of a pacing stimulus and after the sensing of a spontaneous beat. 1970, S.S. Barold et al., “Chest wall stimulation in evaluation of patients with implanted ventricular-inhibited demand pacemakers”, in Br. Heart J., 32(6):783-789

noun

1. A material or piece of material, such as a brick, that has a very high melting point.
2. A plant or factory that produces such material.