Jihadism (also known as jihadist movement, jihadi movement, and variants) is a 21st-century neologism found in Western languages to describe militant Islamic movements perceived as "existentially threatening" to the West and "rooted in political Islam". It has been described as a "difficult term to define precisely", because it remains a recent neologism with no single, generally accepted meaning. The term "jihadism" first appeared in South Asian media; Western journalists adopted it in the aftermath of the September 11 attacks of 2001. It has since been applied to various insurgent and terrorist movements whose ideology is based on the Islamic notion of jihad.