The cotte (or cote) was a medieval outer garment, a long sleeved shift, or tunic, usually girded, and worn by men and women. In medieval texts, it was used to translate tunica or chiton. Synonyms included tunic or gown. It was worn over a shirt (chemise), and a sleeveless surcote could be worn over it. By the sixteenth century it had become a woman's undergarment, later (seventeenth century) it split into an upper 'corps' and a lower 'cotte', or skirt, amongst the poorer classes.
In modern French, it survives in the expression cotte de mailles.
References
Cotte Wikipedia(Text) CC BY-SA