1. 1.national spirit or aspirations.
Dictionary.com Unabridged (v 1.1) - Cite This Source - Share This na·tion·al·ism    Audio Help   ˈnæʃ ə nlˌɪz əm, ˈnæʃ nəˌlɪz-/ Pronunciation Key - Show Spelled Pronunciation[nash-uh-nl-iz-uh m, nash-nuh-liz-] Pronunciation Key - Show IPA Pronunciation –noun
1.national spirit or aspirations.
2.devotion and loyalty to one's own nation; patriotism.
3.excessive patriotism; chauvinism.
4.the desire for national advancement or independence.
5.the policy or doctrine of asserting the interests of one's own nation, viewed as separate from the interests of other nations or the common interests of all nations.
6.an idiom or trait peculiar to a nation.
7.a movement, as in the arts, based upon the folk idioms, history, aspirations, etc., of a nation.
[Origin: 1830–40; national + -ism ]
Dictionary.com Unabridged (v 1.1) Based on the Random House Unabridged Dictionary, © Random House, Inc

2. Devotion to the interests or culture of one's nation.
American Heritage Dictionary - Cite This Source - Share This na·tion·al·ism    Audio Help   (nāsh'ə-nə-lĭz'əm, nāsh'nə-)  Pronunciation Key  n.  
Devotion to the interests or culture of one's nation.
The belief that nations will benefit from acting independently rather than collectively, emphasizing national rather than international goals.
Aspirations for national independence in a country under foreign domination.
na'tion·al·ist adj. & n., na'tion·al·is'tic adj., na'tion·al·is'ti·cal·ly adv. (Download Now or Buy the Book) The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2006 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

3. WordNet - Cite This Source - Share This nationalism noun
1. love of country and willingness to sacrifice for it; "they rode the same wave of popular patriotism"; "British nationalism was in the air and patriotic sentiments ran high" [syn: patriotism] 
2. the doctrine that your national culture and interests are superior to any other [ant: multiculturalism, internationalism] 
3. the aspiration for national independence felt by people under foreign domination 
4. the doctrine that nations should act independently (rather than collectively) to attain their goals [ant: internationalism] 
WordNet® 3.0, © 2006 by Princeton University.

4. Corsican nationalists sometimes shoot or spray on the traffic signs, damaging the French version of names (WIKIPEDIA)

5. "In an anthropological spirit, then, I propose the following definition of the nation: it is an imagined political community - - and imagined as both inherently limited and sovereign.
"It is imagined because the members of even the smallest nation will never know most of their fellow-members, meet them, or even hear of them, yet in the minds of each lives the image of their communion…”
"The nation is imagined as limited because even the largest of them encompassing perhaps a billion living human beings, has finite, if elastic boundaries, beyond which lie other nations. No nation imagines itself coterminous with mankind. The most messianic nationalists do not dream of a day when all the members of the human race will join their nation in the way that it was possible, in certain epochs, for, say, Christians to dream of a wholly Christian planet.”

6. "It is imagined as sovereign because the concept was born in an age in which Enlightenment and Revolution were destorying the legitamcy of the divinely-ordained, hierarchical dynastic realm. Coming to maturity at a stage of human history when even the most devout adherents of any universal religion were inescapably confronted with the living pluralism of such religions, and the allomorphism between each faith's ontological claims and territorial stretch, nations dream of being free, and, if under God, directly so. The gage and emblem of this freedom is the sovereign state.
"Finally, it is imagined as a community, because, regardless of the actual inequality and exploitation that may prevail in each, the nation is always conceived as a deep, horizontal comradeship. Ultimately it is this fraternity that makes it possible, over the past two centuries, for so many millions of people, not so much to kill, as willingly to die for such limited imaginings.”
(Benedict Anderson, 1983)