• noun:   the act of linking together as in a series or chain
• noun:   the linking together of a consecutive series of symbols or events or ideas etc

  Example: "It was caused by an improbable concatenation of circumstances"

• noun:   the state of being linked together as in a chain; union in a linked series
• noun:   a series of things depending on each other as if linked together

  Example: "A complicated concatenation of circumstances"

Related words...