noun
same race; racial identity
Refers to people belonging to the same racial group or the concept of shared racial identity. Often used in sociological or historical contexts.
彼らは同人種であることに誇りを持っている。
They take pride in being of the same race.
同人種間の結婚は当時禁止されていた。
Marriage between people of the same race was prohibited at that time.
人種 simply means 'race' or 'ethnic group', without the 'same' component.
Compound of 同 (どう, 'same') + 人種 (じんしゅ, 'race'). The exact historical derivation is uncertain, but the meaning is transparent from its components.