Simplify the following text for a Grade 16 native English-speaking person.
Original: A not often used definition of ` glaze ' is the highly sintered compacted oxide layer formed due to the sliding of either two metallic surfaces ( or sometimes a metal surface and ceramic surface ) at very high temperatures ( normally several hundred degrees Celsius ) in oxidizing conditions .
Simplified: A not often used definition of glaze is the highly sintered compacted oxide layer formed due to the sliding of either two metallic surfaces ( or sometimes a metal surface and ceramic surface ) at very high temperatures ( normally several hundred degrees Celsius ) in oxidizing conditions .