ʿiddā עִדָּה ‘filth’ (Hebrew)
Etymology?: from an unused root meaning to set a period, compare ʿādā עָדָה ‘to advance / to adorn’, ʿūd עוּד ‘to return / to testify’
ʿiddā n, f
1) menstruation
1a) filthy rag, stained garment (fig. of best deeds of guilty people)