Lexical Definition

‎עֵד‎ ʻêd (ayd) filth ^H:N-F
from an unused root meaning to set a period (compare ‎עָדָה‎, ‎עוּד‎)

filthy.

• the menstrual flux (as periodical)
• by implication (in plural) soiling

1) menstruation
1a) filthy rag, stained garment (fig. of best deeds of guilty people)

Brown-Driver-Briggs

[‎עִדָּה‎] noun feminine menstruation, so Vrss (properly time, period); — plural absolute ‎בֶּגֶד עִדִּים‎ Isa 64:5* i.e. stained garment (figurative of best deeds of guilty people; || ‎טָמֵא‎).

Brown-Driver-Briggs References