Gerund use functioning as an uncountable noun.
Definitions
The act or process of emitting fumes, smoke, or vapour. The constant fuming of the chemicals filled the laboratory with an acrid smell.
An expression or state of intense anger. His silent fuming was more unsettling than if he had shouted.
fumegerund / present participle Functions as an adjective meaning ‘very angry’ or ‘emitting fumes’; derived from the present participle of the verb.
Definitions
Extremely angry; seething with rage. He left the meeting fuming after the unfair decision.