المعنى الاصطلاحي :

The cause that obligates making ablution, ghusl (ritual bath), or dry ablution.

الشرح المختصر :

"Hadath" (ritual impurity) is a Shari‘ah-approved cause and a description that require making ablution, "ghusl" (ritual bath), or their substitute which is "tayammum" (dry ablution). They are of two types: 1. Minor "hadath": which necessitates minor ritual purification, i.e. ablution or "tayammum", such as urinating, defecating, passing wind, and sleeping. 2. Major "hadath": which necessitates major ritual purification, i.e. a ritual bath or "tayammum", such as ejaculation of semen and menses.

التعريف اللغوي المختصر :

"Hadath" (pl. ahdāth): urine or the like that comes out of the anus or genitals. It is derived from "hudooth", which means occurrence, happening anew.