Explained by Leslau as ‘the thing of the women’. The second component of this word-combination,
ḳar can be plausibly compared to the present root, whereas Leslau’s interpretation looks rather a folk etymology.
PS
*ḳry/ˀ - to have effusion (menstruation, pollution)
(SED I No. 37v)
Alternatively, a nominal root *ḳVry/ˀ ‘effusion (menstruation, pollution)’ can be reconstructed, the related verbal forms to be then considered denominal.