al qaeda is most known for their attacks on the twin towers and the pentagon on september 11, 2001
a militant islamist organization, formed by osama bin laden in the 1990s, that has adopted takfiri doctrines and has declared jihad against all westerners and their muslim supporters
"al qaeda is most known for their attacks on the twin towers and the pentagon on september 11, 2001" What is the definition of "al qaeda"?