the word 'tranquilly' is built upon the latin adjective 'tranquillus', which originally described the stillness of the sea or air. the english adjective 'tranquil' was adopted in the early 17th century, preserving this core sense of profound calm. the adverbial form 'tranquilly' was subsequently created by appending the native english suffix '-ly', a highly productive morpheme used to convert adjectives into adverbs. thus, the word's evolution directly maps the latin concept of stillness onto the grammatical function of describing an action performed in a serene manner.

Structure: tranquill (calm, quiet) + ly (adverb suffix) tranquill is from latin 'tranquillus' meaning calm, quiet. ly is an old english suffix forming adverbs from adjectives.