morgan mor·gan (môr'gən)
Abbr. M A unit for expressing the relative distance between genes on a chromosome based on the frequency with which the genes cross over; one unit equals a theoretical crossover value of 100 percent between two loci.
Morgan Mor·gan (môr'gən), Thomas Hunt. 1866-1945.
American biologist. He won a 1933 Nobel Prize for establishing the chromosome theory of heredity by his studies of the fruit fly Drosophila.