To surge or foam as if boiling. (Dictionary.com)
To be in a state of agitation or excitement. (Dictionary.com)
To feel very angry but to be unable or unwilling to express it clearly. (Cambridge Dictionary)
To soak or saturate in a liquid. (Merriam – Webster)
When you are seething, you are very angry about something but do not express your feelings about it. (Collins Dictionary)
If you say that a place is seething with people or things, you are emphasising that it is very full of them and that they are all moving about. (Collins Dictionary)
(of a liquid) boil or be turbulent as if boiling. (Oxford Dictionaries)
Acosta: Trump Is “Seething” Over Cohen Sentence.
Source: Trump ‘seething’ about Cohen, says ‘he’s a liar’.
They Threaten, Seethe and Unhinge, Then Kill in Quantity.