also: かいご
noun
Archaic word for 'egg' or 'eggshell'. In modern Japanese, たまご is used for 'egg' and 卵の殻 for 'eggshell'. Found only in classical texts or historical contexts.
古語では「かい」は卵を意味した。
In classical Japanese, 'kai' meant egg.
この古文書には「卵」という表記が見られる。
In this old document, the notation '卵 (kai)' can be seen.
The historical derivation is uncertain. かい is an archaic native Japanese word for 'egg' or 'eggshell', largely replaced by たまご in modern usage.