- 1: resisting control or authority : stubborn, unmanageable
- 2a : resistant to treatment or cure <a refractory lesion>
- b : unresponsive to stimulus
- c : immune, insusceptible <after recovery they were refractory to infection>
A refractory material is one that retains its strength at high temperatures. ASTM C71 defines refractories as "non-metallic materials having those chemical and physical properties that make them applicable for structures, or as components of systems, that are exposed to environments above 1,000 °F (811 K; 538 °C)".