What does backcross mean?
A backcross is a controlled mating between a hybrid organism and one of its parents, or with an individual so genetically similar to that parent as to be effectively equivalent. The technique is a cornerstone of classical genetics and modern breeding: by repeatedly crossing a hybrid back to the desired parent—known as the recurrent parent—scientists can retain one valuable trait, such as disease resistance, while restoring all the other characteristics of an elite variety. The term functions as both a noun, naming the cross itself or a resulting generation, and a verb describing the act of making such a cross. It appears almost entirely in technical literature on plants, animals, and laboratory organisms like mice, and is unfamiliar outside scientific circles, yet the concept underlies much of the food supply and many biomedical research strains. Its precision and long history make it a defining word in the vocabulary of heredity.
A cross between a hybrid organism and one of its parents, or an individual genetically similar to that parent; also, a generation produced by such a cross.
"The first backcross showed that the dwarfing allele came from the wild parent."
Often qualified by number, as in 'first backcross' or BC1, BC2 generations.
To mate or cross a hybrid organism with one of its parents or with an individual genetically similar to that parent.
"Breeders backcrossed the introgressed line four times to eliminate unwanted wild traits."
Commonly used transitively with the recurrent parent specified.
Standard pluralization; commonly seen when referring to successive backcross generations in breeding programs.
"After several backcrosses, the line differed from the recurrent parent at only a handful of loci."
Plant breeders have used backcrossing for over a century to smuggle a single valuable gene—like disease resistance—into an elite crop variety without ruining everything else that makes it good.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of backcross
The word was coined in the early twentieth century alongside the rise of modern genetics, formed transparently from English 'back' plus 'cross,' the latter already established in animal- and plant-breeding vocabulary through terms like crossbreed and intercross. It entered scientific use as Mendelian breeders needed precise names for directional crossing strategies, and it remains stable across British and American usage with no significant regional variation. Its relatives—crossover, outcross, crisscross—all descend from the same breeding sense of 'cross' rather than any classical root.
Related word forms
How backcross is actually used
A technical term used almost exclusively in genetics, plant and animal breeding, and laboratory science; rarely encountered in everyday speech. In breeding contexts, the genetically similar parent repeatedly used in the cross is called the 'recurrent parent.'
Easily confused with backcross
An outcross mates an organism with an unrelated individual of the same species to introduce new variation, whereas a backcross mates it with a parent or closely related individual to recover parental traits.