ὀξύς + γενής

In 1777, Antoine Lavoisier needed a name for the gas that Joseph Priestley had isolated three years earlier. Lavoisier combined two Greek words: oxys, meaning sharp or acid, and genes, meaning born or producing. He called the element oxygène -- the acid-producer -- because he believed it was the essential component of all acids. He was wrong. Hydrochloric acid contains no oxygen at all.

The Greek word oxys had a long history before Lavoisier borrowed it. It meant sharp, keen, or pointed. An oxytone in Greek grammar was a word with a sharp accent on the last syllable. Vinegar was oxos -- the sharp liquid. The leap from sharp taste to acid was natural enough, and Lavoisier trusted it completely.

Priestley, working in England, had called the gas dephlogisticated air. Carl Wilhelm Scheele in Sweden had isolated it even earlier, in 1771 or 1772, but his publisher delayed the findings. Lavoisier's name won because his theory won. The oxygen theory of combustion replaced phlogiston, and the name followed the theory into every textbook.

The error in the name was recognized within Lavoisier's own lifetime. Humphry Davy proved in 1810 that hydrochloric acid contained no oxygen. But by then the word was entrenched in every European language. German tried Sauerstoff (sour-stuff), which is equally wrong but at least honestly descriptive. The rest of the world kept Lavoisier's Greek coinage, mistake and all.