the GNU version of the Collaborative International Dictionary of English
n. The physiological individual, characterized by definiteness and independence of function, in distinction from the morphological individual or morphon.
The Century Dictionary and Cyclopedia
n. A terra introduced by Haeckel to designate a physiological individual as contrasted with a morphon or morphological individual.
Word Usage
"The device, called a bion, is a rechargeable battery-powered electrode, similar in size to a matchstick."