The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
NOUN: A tough and aggressive or violent youth.
ETYMOLOGY: Origin unknown.
OTHER FORMS: hooli·gan·ism —NOUN
The American Heritage® Dictionary of the English Language, Fourth Edition. Copyright © 2000 by Houghton Mifflin Company. Published by the Houghton Mifflin Company. All rights reserved.
From the Online Etymology Dictionary:
1890s, of unknown origin, first found in British newspaper police-court reports in the summer of 1898, almost certainly from the surname Houlihan, supposedly from a lively family of that name in London (who figured in music hall songs of the decade). Internationalized 20c. in communist rhetoric as Rus. khuligan, opprobrium for "scofflaws, political dissenters, etc."
(Edited to add etymology)