Monsoon is a borrowed word for a borrowed season — from the Arabic mawsim, a time, a fixed time, the appointed turning of the wind that sailors had to know to cross the Indian Ocean and live. Before it was weather it was a word, and before it was a word it was a thing you could die for not understanding.
The names of the natural world were given by the people who lived closest to it. A jungle, a monsoon, a jaguar — these came into English from the languages of those who had stood under that rain, walked that forest, met that animal in the dark. The word is a kind of testimony: someone was here first, and paid attention, and named what they saw.
I think this is why nature words feel older than the rest. They were never invented in a study. They were worn into shape by use, by people who needed them to be exact because their lives turned on the difference between one wind and another.
These are the word origins the earth gave us — the etymology of storms, rivers, animals, and the wild places we borrowed our names from. Each one carries the fingerprint of a first observer we'll never meet.
We say we name nature, as if the naming were ours to do. But mostly we inherited names already made, from people who knew the land in a way we no longer do. The word monsoon outlived the sailors who needed it. It still arrives every year, on time, indifferent to whether we remember where the word came from — or that it was ever a matter of survival at all.