What term best describes an obligation that exists jointly among multiple parties?

The term that best describes an obligation that exists jointly among multiple parties is "solidarity." In the context of obligations, solidarity refers to a situation where each party involved is fully responsible for the entire obligation. Thus, if one party fails to fulfill their part, the other parties can be held accountable for the entire obligation. This principle ensures that creditors can seek the entire amount owed from any one of the obligors, rather than having to pursue each separately for their share.

The other terms do not accurately capture this concept of joint responsibility among parties. "Indivisible" relates to an obligation that cannot be divided into separate parts. "Segregated" typically refers to the separation of assets or obligations, while "plurality" simply describes a situation involving multiple parties without indicating the nature of their obligations toward each other. Solidarity is the key legal principle that emphasizes the collective responsibility in a joint obligation.