relationship

noun

• Connection or association; the condition of being related.
• The links between the x-values and y-values of ordered pairs of numbers especially coordinates.
• Kinship; being related by blood or marriage.
• A romantic or sexual involvement.

  "They have been in a relationship for ten years, but have never married."

• A way in which two or more people behave and are involved with each other

  "I have a good working relationship with my boss."

• The level or degree of affinity between keys, chords and tones.