An organism that has two of the same alleles for a specific trait is referred to as being homozygous for that trait. In genetics, alleles are different versions of a gene that determine a specific characteristic. For instance, if we take a gene that determines flower color in plants, one allele might produce red flowers, while another might produce white flowers. If a plant carries two alleles for red flowers (RR), it is homozygous for that trait.
Being homozygous can be important in understanding how traits are inherited. If both alleles are the same, the organism will express that specific trait. This can have implications for breeding, population genetics, and the expression of certain diseases in animals and humans. In contrast, if an organism has different alleles for a trait (for example, one red allele and one white allele), it is described as heterozygous.