This term is defined in ECSS-E-ST-35-10C as
reaction of the engineering material with its environment with a consequent deterioration in properties of the material

This term is defined in ECSS-Q-ST-70-08C as
deterioration of a metal by chemical or electrochemical reaction with its environment

This term is defined in ECSS-Q-ST-70-14C as
gradual degradation of materials produced by chemical reaction with the environment or with fluids in contact with materials