While the word "gene" is often associated with the pioneering work of Gregor Mendel in the 19th century, he never actually used the term.

The first recorded use of the word "gene" is attributed to Wilhelm Johannsen in 1909. Johannsen, a Danish botanist, was working on the concept of heredity and needed a term to describe the units of inheritance that Mendel had theorized about. He coined the term "gene" from the Greek word "genos," meaning "birth" or "origin."

So, while Mendel laid the groundwork for our understanding of genes, it was Johannsen who gave them their name.