ETYMOLOGY
from Latin irruentem, present participle of irruere (to rush in or upon)
EXAMPLE
“… Under such an irresistible impulsion, mind and soul both were now following hand in hand a new path of progressive and irruent development. …”
From: Music: A Monthly Magazine
Devoted to the Art, Science, Technic, and Literature of Music
W. S. B. Mathews, Editor
Volume IV. May, 1893 to October 1893
The Old Lyric Stage and the New One
Lexicophilia 