This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
埿 is a rare character. It visually combines 泥 (mud) and 土 (earth), but the exact historical development is uncertain.
The kanji stacks 泥 (mud) on top of 土 (earth), like thick mud covering the ground. This may suggest something related to mud or plastering, but the exact meaning is unclear.
For デイ, imagine a muddy day where the earth is covered in thick mud: day -> デイ, and the mud 泥 sits on the earth 土.