Gerundial noun referring to the process or state of becoming septic, rotten, or increasingly problematic.
festeringgerund / present participle Used attributively to modify nouns; derives from the verb 'fester' but functions as a participial adjective.
The festering wound needed immediate medical attention.
Гноящаяся рана требовала немедленного медицинского вмешательства.
The festering resentment between the two colleagues eventually led to a confrontation.
Тлеющее недовольство между двумя коллегами в конечном итоге привело к столкновению.