The most famous thing about Rudolf Diesel is how his life ended, but the word he left behind is a plain surname that became a common noun.

Diesel was born in Paris in 1858 to Bavarian parents. The family moved to London during the Franco-Prussian War, and at twelve he was sent to relatives in Augsburg, where he finished school and won a scholarship to the Royal Bavarian Polytechnic in Munich. One of his professors there was Carl von Linde, the refrigeration pioneer, who later employed him.

In 1892 Diesel was granted a German patent for an internal combustion engine, and in 1893 he published his theory. That theory turned out to be partly wrong, and he filed a new application the same year. The engine that actually worked was shown in 1897: a single-cylinder, four-stroke machine of 25 horsepower, according to Britannica. Instead of a spark plug, it squeezed air until it was hot enough to ignite the fuel. Its efficiency made it a quick commercial success.

English picked up his name almost at once. Etymonline and Merriam-Webster both record "diesel" for this type of engine in 1894, three years before the successful 1897 model. Merriam-Webster defines diesel fuel as fuel designed for use in diesel engines, so the fuel is named by reference to the machine. Diesel tested various fuels, and Wikipedia says that included vegetable oil.

Diesel died mysteriously. On 29 September 1913 he boarded the steamer Dresden at Antwerp, bound for London. He was last seen going to his cabin. The next morning his bed was unused, and his hat and folded coat were found on deck, according to Wikipedia.

On 10 October a decomposed body was found at sea. Wikipedia says a Dutch pilot boat crew recovered it in the Eastern Scheldt, kept some personal items, and returned the body to the water. His son identified the items on 13 October. History.com gives a different account of who spotted the body, so the details of the find vary by source.

So he did not vanish without trace, as the story is sometimes told. What nobody knows is how he went overboard. Suicide, murder and a staged disappearance have all been proposed, and Wikipedia calls the case unresolved. Wikipedia says his wife found records suggesting his finances were depleted, and History.com says he was nearly broke, though Britannica says royalties had made him wealthy. Rumors of murder by oil interests or to block a patent sale circulated in the press.

The engine, the fuel and the verb-like adjective in "diesel truck" all trace back to one man's surname.