Wiktionary
underrobe
n. A robe designed to be worn under other clothing, particularly another robe.
Usage examples of "underrobe".
Musui also had on a short white underrobe and a black outer one and muddy brown gaiters.
Except for the sleeves, the underrobe was rather plain, almost severe, and she knew it would cling to the planes of her body like a second skin.
In a stall in the rear, she changed out of her outer Chinese robe, but kept the underrobe that Hunter had provided to make the Chinese robe more comfortable.
When he felt ready to move on, he dressed by himself, pulling on his cotton underrobes, then wrestled his arms and legs into stiff riding leathers.