also: しゅみーず
noun
chemise; slip; undershirt
A woman's undergarment, typically a lightweight, sleeveless slip worn under clothing. Loanword from French 'chemise'.
from French
夏はシミーズ一枚で過ごすこともある。
In summer, I sometimes spend the day in just a chemise.
彼女はシルクのシミーズを着ていた。
She was wearing a silk slip.
Borrowed from French 'chemise', likely via early 20th-century fashion terminology. The alternate reading シュミーズ reflects an older or variant approximation of the French pronunciation.