sound symbolism
Definition - The phenomenon where a word's sound calls to mind its meaning, e.g. sneer and mellifluous. As opposed to onomatopoeia, where the word imitates the sound it stands for, e.g. crash and oink.

Quotation -
Sound symbolism, for its part, was no friend to the American woman in the throes of labor who overheard what struck her as the most beautiful word in the English language and named her newborn daughter Meconium, the medical term for fetal excrement.
(Source: Steven Pinker, Words and Rules)

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