البصير
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Surrounding an interval of purity with two menses.
"Ihtiwāsh" (surrounding purity with menses) refers to the period of purity between two menses. It is as if the menstrual blood encompasses the period of purity and covers it from the beginning to the end. In other words, the woman's period of purity is surrounded by two menses.
"Ihtiwāsh": Derived from "ihtawasha", which means surrounding/centering someone or something. Originally meaning of "hawsh": collecting, joining together.