Zoon definition

First adopted by Herbert Spencer in Principles of Biology (see 1864 quotation): from , from .

:
1. An animal which is the sole product of a single egg.
2. Any one of the perfectly developed individuals of a compound animal.

1864: Herbert Spencer, Principles of Biology, page 205, § 73 (1868 reprint; D. Appleton & Co.)

[… A] zoological individual is constituted either by any such single animal as a mammal or bird, which may properly claim the title of a zoon, or by any such group of animals as the numerous Medusæ that have been developed from the same egg, which are to be severally distinguished as zooids.