Webster's Revised Unabridged Dictionary · 1913

Kirtle

Kirtle , noun

[Old English kirtel, curtel, Anglo-Saxon cyrtel; skin to Icelandic kyrtill, Swedish kjortel, Danish kiortel, kiole.]

A garment varying in form and use at different times, and worn both by men and women.
Wearing her Norman car, and her kirtle of blue. — Longfellow

The term is still retained in the provinces, in the sense of “an outer petticoat.”