female genitalia, vulva, (kokuji)
𡱖 is a rare kokuji (Japanese-made kanji) for female genitalia, specifically the vulva. Its meaning is narrow and anatomical, with no clear conceptual extensions beyond that.
𡱖 is a kokuji, likely created in Japan by combining 尸 (body) and 木 (tree/wood) to represent a specific anatomical meaning. The exact historical reasoning is uncertain.
Under the body radical 尸, a wooden shape 木 suggests a hidden, natural part of the body: the vulva.
For つび, imagine two bees (つび) buzzing around a wooden hive under a body-shaped roof: つび -> つび, and the hidden hive represents the vulva.