المعنى الاصطلاحي :

A belief based on the claim that the existence of Allah and the existence of His creation are one and the same.

الشرح المختصر :

"Wahdat al-wujood" (unity of existence) is an atheistic ideology resulting from thorough belief in the idea of "hulool" (Allah's incarnation in some of the created beings). It entails that nothing exists except Allah, that everything in existence represents Allah, that the Creator and His creation are inseparable, and that the existence of all creation is unreal save the existence of Allah. They allege that everything that exists is the shadow of Allah (a theophany of His essence). They, thus, denied the fact that Allah is the Lord of the worlds, and they did not make a distinction between the Lord and the servant. It is a Hindu-Buddhist-Magian ideology. Those who advocated "wahdat al-wujood", such as Ibn ‘Arabi at-Tā’i, Ibn Sab‘een, and their followers, based their doctrine on the claim that the essence of the definite existence of the eternal creator is the very essence of the possible existence of everything that is created and brought into being. Hence, they confused the existence of the Creator with the existence of the creation to such an extent that they thought that Allah's existence is the very existence of the creation. This is because all created beings share the description of existence, so they considered the existence as one in essence an did not differentiate between the one in essence and the one in kind.