Which legal term describes an interested third party who wishes to become involved in a lawsuit?

The legal term that describes an interested third party wishing to become involved in a lawsuit is "intervenor." An intervenor is someone who is not originally a party to the case but has a significant interest in the outcome and seeks to join the proceedings to protect that interest. This participation is typically formalized through a motion for intervention, which the court must grant for the intervenor to participate in the case.

In contrast, "amicus curiae" refers to a friend of the court, who provides information or expertise but does not seek to become a party to the litigation. "Considerant" is not a recognized legal term in this context. "Litigant" refers to a party engaged in a lawsuit, which does not encompass third parties wanting to intervene. Thus, "intervenor" most accurately captures the concept of a third party actively seeking involvement in a legal dispute.