Dynamite very nearly had a gentler name. According to Wikipedia, Alfred Nobel first planned to sell it as "Nobel's Safety Powder."
The word safety was not an accident. Nobel's family business worked with nitroglycerin, a liquid explosive that was powerful but dangerously unstable. The Nobel Prize's own biography says there were several explosions. The worst, in 1864, killed his brother Emil and several other people.
Emil Nobel was 20. He died on September 3, 1864, at his father's factory at Heleneborg in Stockholm, along with other workers. Alfred kept working on the same substance.
His answer was to soak it up. Mixing nitroglycerin with kieselguhr turned the liquid into a paste that could be shaped into rods. Kieselguhr, or diatomaceous earth, is made of fossilized algae. Wikipedia says Nobel's supply came from the Elbe, near his factory at Hamburg. He also invented a detonator, a blasting cap that could be set off by lighting a fuse.
Nobel made the discovery in 1866. He patented it in England on May 7, 1867, and in Sweden on October 19 of the same year. By then he had dropped the safety name for something punchier.
He took it from Greek. Dynamis means "power," and Etymonline traces it to dynasthai, "to be able, to have power." Nobel added -ite, a suffix used for minerals and other substances. The result was a name that sounded like pure force.
English soon did more with it. Etymonline records the verb "to dynamite" from 1878. By 1922, dynamite could also mean anything potentially dangerous. By the mid-1960s it had flipped into praise: a dynamite song was an excellent one. Etymonline suggests this slang may have come from African-American speech.
The Greek root was already busy in English before Nobel. Dynamic, meaning related to force, is recorded from 1812. Dynasty, a line of rulers, comes from the same family of words about power.
So the name Nobel chose was never really about safety. It was about power, and the word has kept that charge in every sense it has picked up since.