əˈfɪnɪti a natural attraction or feeling of kinship an affinity for politics the mysterious affinity between them James's affinity with Sam inherent resemblance between persons or things the force attracting atoms to each other and binding them together in a molecule basic dyes have an affinity for wool and silk (immunology) the attraction between an antigen and an antibody a close connection marked by community of interests or similarity in nature or character found a natural affinity with the immigrants felt a deep kinship with the other students anthropology's kinship with the humanities (biology) state of relationship between organisms or groups of organisms resulting in resemblance in structure or structural parts in anatomical structure prehistoric man shows close affinity with modern humans (anthropology) kinship by marriage or adoption; not a blood relationship