Sufism

n. mystical Islamic movement based on the belief that union with God is possible only through intense and impassioned worship

Sufism is a mystic tradition within Islam that encompasses a diverse range of beliefs and practices dedicated to Divine love and the cultivation of the elements of the Divine within the individual human being. Practitioners of this tradition are known as "Sufis" generally, though some senior members of the tradition reserve this term for those who have attained the goals of the tradition.
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Noun
1. Islamic mysticism
(hypernym) mysticism, religious mysticism

(n.)
A refined mysticism among certain classes of Mohammedans, particularly in Persia, who hold to a kind of pantheism and practice extreme asceticism in their lives.
  

Sufism is a term that designates Islam's mystical and ascetic movements. A Sufi is one who practices Sufism. Sufis attempt to go beyond the restrictions of a "typical" moslem life and to seek Allah in more intimate ways. They strive to break down the barriers between themselves and Allah by replacing their human characteristics with divine ones. In many ways, this is similar to the Buddhist's attempts to reach enlightenment (the realization that all is one). Since Allah is one himself, the attempt to reach him can become the realization of the oneness of all things. Sufis focus on three kinds of mysticism to accomplish this: love mysticism (see Rabia ), ecstatic mysticism, and intuitive mysticism (see Smith, pp. 259-261). There has always been a tension between Sufism and classical Islam because many of the beliefs, actions, and statement of Sufism appear heretical to non-Sufis.