Danish botanist Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity.
He also made the distinction between the outward appearance of an individual (phenotype) and its genetic traits (genotype).
Four years earlier, William Bateson, an early geneticist and a proponent of Mendel's ideas, had used the word genetics in a letter; he felt the need for a new term to describe the study of heredity and inherited variations. But the term didn't start spreading until Wilhelm Johannsen suggested that the Mendelian factors of inheritance be called genes.
The proposed word traced from the Greek word genos, meaning "birth". The word spawned others, like genome.
Last Reviewed: April 22, 2013