intervenor

or in·ter·ven·er

[in-ter-vee-ner]

noun

a person who intervenes, especially in a lawsuit.

Origin of intervenor

First recorded in 1615–25; intervene + -or2
Related formsnon·in·ter·ven·er, nounnon·in·ter·ve·nor, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019