Intervention
late Middle English: from Latin interventio(n- ), from the verb intervenire (see intervene).
wiktionary
From Middle French intervention, from Latin interventiō
Morphologically intervene + -tion.
etymonline
intervention (n.)
early 15c., intervencioun, "intercession, intercessory prayer," Late Latin interventionem (nominative interventio) "an interposing, a giving security," literally "a coming between," noun of action from past-participle stem of Latin intervenire "to come between, interrupt," from inter "between" (see inter-) + venire "to come" (from a suffixed form of PIE root *gwa- "to go, come"). Later "act of intervening" in any way; in 19c.-20c. often of international relations; by 1983 of interpersonal intrusions by friends or family meant to reform a life felt to be going wrong.
