Definition of "irruptive" [ir•rup•tive]

• Irrupting or tending to irrupt. (adjective)
• Geology Intrusive. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "They are unusual in that they do not 'migrate' south during the winter, but they do undergo 'irruptive dispersal', that is moving out of their breeding areas when their main prey, the lemming, suffers a declining population."
• "There are no foreseeable human-related threats to wolverines Lynx Lynx are cyclic or irruptive in the Alaskan Arctic, and in areas where snowshoe hares become periodically abundant, lynx can become abundant."
• "Ereignis is a word for that irruptive dimension, the historical point at which thought can latch onto Being: it is equally implicated in thought, being, and history."