simmer
UK[ˈsɪmə(r)]US[ˈsɪmər]
v
To cook something by keeping it almost at boiling point, with small bubbles forming slowly on the surface.
v
To feel a strong emotion, especially anger, which is controlled only with difficulty.
v
To develop slowly, without being obvious.
Etymology
The verb 'simmer' is an alteration of the earlier English dialect word 'simper', which shared the same meaning of gentle boiling. Both words are ultimately onomatopoeic in origin, imitating the low, hissing or bubbling sound made by liquid cooking just below the boiling point. This sound symbolism directly gave rise to the primary culinary meaning. The semantic extensions to suppressed emotions or latent situations are metaphorical, drawing a parallel between contained, bubbling liquid and feelings or developments that are present but not yet fully expressed or erupted.
Analysis
The word 'simmer' is a simplex word of imitative origin. It is not productively composed of separable morphemes in modern English.
Examples
Let the soup simmer for twenty minutes to allow the flavors to blend.
He was simmering with rage after hearing the unfair criticism.
A plan was simmering in the back of her mind for months before she acted.