Al-Ḥadath al-Akbar (Arabic: الحدث الأکبر) (major ritual impurity) is an act that causes the obligation of ghusl or the state occurs for one as a result of these acts and one is not allowed to perform the acts that are subject to tahara. Some common major hadath are: janaba, hayd and touching a dead body.
Hadath is something that invalidates tahara (ritual purity). However, some faqihs hold that it is also a state that occurs for a person after certain acts, such as: urinating, janaba, hayd or touching a dead body, and the person is not allowed to perform the acts that are subject to tahara. The rulings about hadath are discussed in jurisprudential books and Manual of Islamic law. A person to whom a hadath has occurred is called muhdith.
Faqihs have divided hadath into al-hadath al-akbar (major ritual impurity) and al-hadath al-asghar (minor ritual impurity). By al-hadth al-akbar they mean what causes the obligation of ghusl, such as: janaba, sexual intercourse, hayd, nifas, medium or excessive istihada, or touching a dead body (that is cold and is not given ghusl al-mayyit).