The ANBU (暗部, The ANBU? literally "Dark Side", Viz "Black Ops", English TV "ANBU Black Ops") is actually short for Ansatsu Senjutsu Tokushu Butai (暗殺戦術特殊部隊, Ansatsu Senjutsu Tokushu Butai? literally Special Assassination and Tactical Squad). The name is a play on words, as in English acronyms like SWAT, where the two kanji used to abbreviate the group's full name constitute an actual word on their own. The ANBU wear porcelain animal masks in order to distinguish themselves from normal shinobi and to conceal their identities. They also have standard uniforms consisting of black and gray armor, arm guards, and a signature spiral tattoo on their arms. Certain ANBU wear black cowls over their standard uniforms, and squad leaders may wear white cowls. ANBU protect the village from exceptional threats, conduct high-risk missions into enemy countries, and deal with extremely strong ninja. They are also responsible for carrying out assassinations and missions requiring specially trained ninja. Unique for most characters in Naruto, all ANBU carry Ninjaken, which are usually strapped to their backs, and they all know the layout of the human body in detail. By using Temporary Paralysis Technique (金縛りの術, Kanashibari no Jutsu?, English TV "Paralysis Jutsu"), ANBU members can paralyze an opponent, leaving them open for attack. With Time Reversal Technique (時逆の術, Jigyaku no Jutsu?), an ANBU can put someone in a state of reverse hypnosis, allowing them to remember details that they otherwise would not. ANBU is an organization that serves under the direct command of their Kage. Kakashi Hatake was a former captain and Itachi Uchiha became an ANBU captain at age 13. Ibiki Morino, the proctor of the first Chunin exam, is the head of the Konoha ANBU Torture and Interrogation Squad (木ノ葉暗部拷問・尋問部隊, Konoha Anbu Gōmon/Jinmon Butai?). Zabuza Momochi and Raiga Kurosuki were once part of Kirigakure's ANBU. Source: http://en.wikipedia.org/wiki/Naruto_ninja_ranks#ANBU

im pretty sure the question asks : What does "ANBU" stand for....not what does ANBU stand for and what is there role and what do they do in naruto and what is there history...

Okay 1st u know in the forest when there was a test... There were guys in masks saving that teacher, those are ANBU Or if u watched when there was a bad old man and naruto was his friend... After that people in mask came and hypnoticed him and went though his memory asking him questions... those are ANBU if u still dont know what im talking about... go to photobucket.com and type in ANBU if u dont have photobucket go to google images and type in AMBU... Good luckk

It stands for ANsatsu Senjutsu Tokushu BUtai, (Yes I know they shorten it weirdly, but it would sound weird if it were ASTB xD) which translates to Special Assassination and Tactical Squad. Of course I laugh a bit because those poor saps have yet to kill anyone, and only get killed themselves xP.

is associated strongly with the Fuuma clan due to their relationship with Oda Nobunaga and his army. Ultimately, however, the Fuuma proved fleeting, and may or may not have given Nobunaga's army false information that led to his defeat at Sekigahara.

Two good answers. Oh well, I guess all I can say is that, whenever you hear a Japanese acronymof something remember that Japanese is terrible for making acronyms. (Personally I think its impossible to make a true acronym because the language in written form is not condusive to such things)

Ops special team of mercenaries..

this should answer your question- http://naruto.wikia.com/wiki/ANBU