Существительное среднего рода, чаще употребляется во множественном числе.
relationshipNeutral and most common equivalent for mutual relations between people or things. Их взаимоотношение было очень крепким.
Their relationship was very strong.
interactionUsed when the focus is on reciprocal action or mutual influence. Взаимоотношение между учителем и учеником играет важную роль в обучении.
The interaction between the teacher and the student plays an important role in learning.
interrelationshipMore formal and analytical; emphasizes mutual dependence or reciprocal relation. relationFormal and neutral; often used in academic or analytical contexts. relationsUsually plural in English; natural for collective mutual relations, especially social or family ties.