Ghusl in Islam is to pour pure water over one’s body in a special way with the intention of worshipping Allah. And it is obligatory in some cases like semen discharge, converting to Islam, after menstruation.  

Ghusl, or taking a bath

Definition:

Definition: The Arabic word ghusl means to take a bath to wash the whole of one’s body. In the Islamic context it means pouring pure water over the entire body in a particular way, with the intention of worshipping  Allah by uplifiting the state of major ritual impurity.[1]

Ruling: 

The ghusl is obligatory when there is a cause requiring it.

A number of hadith reported by the Prophet’s (peace be upon him) Companions explaining how the ghusl should be performed clearly indicate that it is obligatory.

Taking a bath, i.e. performing the ghusl, is obligatory in the following cases:

1-The ejaculation of semen as per the ayah mentioned above.

 However, if the discharge is in a wet dream, it still requires a bath, even if the sleeper does not feel the orgasm. The Prophet (peace be upon him) was asked whether a woman must take a bath if she had a wet dream.

 This is agreed by all scholars. It is important to note that the discharge of semen without an orgasm, as in the case of illness, does not require a ghusl, and the same is the case for one who sees a sexual dream but there is no trace of a discharge of semen. On the other hand, if on rising from sleep, one feels wetness but cannot remember a wet dream, one must perform the ghusl if one ascertains that the wetness is semen. Moreover, if one finds on one’s clothes traces of a discharge of semen but cannot ascertain its time, and he has already prayed once or more, he should perform the ghusl and repeat any prayer he offered since his last sleep.

2-The insertion of the top of the penis into a woman’s vagina, even if no discharge takes place.

 In this case, taking a bath is obligatory for both man and woman.

3- Embracing Islam by an unbeliever. 

This applies also to an apostate when he reverts to Islam.

4-When a woman finishes her menstrual period or postnatal bleeding. A’ishah reports that the Prophet (peace be upon him) said to Fatimah bint Abi Hubaysh:

It is universally agreed that postnatal bleeding is treated in the same way as menstruation.

5-Death. When Zaynab, the Prophet’s (peace be upon him) eldest daughter, died,