intr.v. in·ter·vened, in·ter·ven·ing, in·ter·venes
a. To involve oneself in a situation so as to alter or hinder an action or development: "Every gardener faces choices about how and how much to intervene in nature's processes" (Dora Galitzki).
b. To interfere, usually through force or threat of force, in the affairs of another nation.
c. Law To enter into a lawsuit as a third party to assert a claim against one or both of the existing parties.
2. To come, appear, or lie between two things: You can't see the lake from there because the house intervenes.
3. To come or occur between two periods or points of time: A year intervened between the two dynasties.
4. To occur as an extraneous or unplanned circumstance: He would have his degree by now if his laziness hadn't intervened.
[Latin intervenīre : inter-, inter- + venīre, to come; see gwā- in the Appendix of Indo-European roots.]
in′ter·venor, in′ter·vener n.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.