"Simmering" Natural Recordings by Native Speakers
To be simmering means to be calmly and quietly boiling or bubbling, typically with a steady and gentle movement. Metaphorically, to be simmering also means to be seething with emotions or ideas, building up energy and tension that may eventually erupt.
I couldn't find any definition or meaning of the word "similitudinary". It appears to be a non-existent or made-up word.