seething
v. C1 Advanced US //ˈsiðɪŋ// UK //sˈiːðɪŋ// seething
v. to feel very angry or frustrated inside, even if you do not show it on your face. It is like having a fire burning in your stomach.
v. to feel intense anger or frustration internally, often without outward expression. Frequently used in the present participle form to describe a state of suppressed rage.
He was seething after the manager insulted him in front of everyone.
The crowd was seething with anger as the referee made a controversial decision that changed the game's outcome.
The diplomat remained calm on the surface, but he was seething with frustration at the lack of progress during the negotiations.
From Middle English sethyng; equivalent to seethe + -ing.