The definition of Test Cross or Back Cross is as under:-
Test cross is a simple method devised by Mendel to verify the genotype of the F1 hybrid.
When the F1 hybrid is crossed with the homozygous recessive parent, it is called a Test Cross.
Since the F1 is crossed back with one of the parents, it is also called the back cross.
Test cross is also used for checking the correctness of Mendel’s law of segregation. (using a monohybrid test cross) and the law of independent assortment of characters (using a dihybrid test cross).