"AFFINITY"

AFFINITY
(Noun)
Meaning:

• A natural attraction, liking, or feeling of kinship.
• An inherent similarity between persons or things.
• Biology. A relationship or resemblance in structure between species that suggests a common origin.
• Immunology. The attraction between an antigen and an antibody.
• Chemistry. An attraction or force between particles that causes them to combine.
• The quality or state of being alike (see images)
  Root: Middle English affinite, from Anglo-French or Latin; Anglo-French affinité, from Latin affinitas, from affinis bordering on, related by marriage, from ad- + finis end, border