What is the meaning of 袿?

open-sleeved robe worn over the 単衣 (hitoe). Women wore one layer in the summer, and between three and eight otherwise. Towards the end of the Heian period the number of uchiki layers was fixed at five.

Also worn by men with 直衣 (nōshi) or 狩衣 (kariginu), sometimes called 衵 (akome)

Source: wiktionary.org