intr.v. ir·rupt·ed, ir·rupt·ing, ir·rupts
1. To break or burst in: The boys irrupted into the kitchen.
2. Ecology To increase rapidly in number, especially beyond the normal range: snowy owls that irrupted southward.
[Latin irrumpere, irrupt- : in-, in; see IN-2 + rumpere, to break; see reup- in the Appendix of Indo-European roots.]
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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.