An Etymological Dictionary of Astronomy and Astrophysics

1. Act of regenerating; state of being regenerated.
   

2. Electronics: A feedback process in which energy from the output of an amplifier is fed back to the grid circuit to reinforce the input.
   

3. Biology: The restoration or new growth by an organism of organs, tissues, etc., that have been lost, removed, or injured (Dictionary.com).

See also: → re-; → generation.