Adjective. Of, or pertaining to, positrons.
Most usage of the word is found in the stories of Isaac Asimov or episodes of Star Trek: The Next Generation, although a Google search finds it a useful name for businesses wanting to convey a futuristic or scientific bent ("Positronic Industries," "Positronic Design," "Positronic Solutions," etc). However, nuclear physicists who study the positron have found it a useful adjective in describing their science.
Physical Letters Review published a paper by Nan Jiang and David M. Schrader (7 December 1998) in which they predict the stability of positronic water, Ps2O, in which the pair of hydrogren atoms is replaced by a pair of positronium atoms. Sure, it would only last 220 picoseconds or so (roughly one fifth of a billionth of a second) before the anti-matter and matter combination annihilated itself. "Anti-water" might make good headline copy but "positronic" is more accurate.
Jim Mitroy of Northern Territory Univeristy in Australia has predicted and described positronic atoms (including positronic forms of calcium, copper, sodium, and helium)-- exotic atoms which contain one or more positrons (and wich would also have a very, very short life).
Scientific acceptance is far from certain, however, as the Max Planck Institute and the University of Michigan, both of which study positrons, refrain from using the word on their respective Web sites or in the titles of their investigators' published papers.
Ball, Philip. "Drip, drip, bang!" Nature News Service. 17 December 1998. <http://www.nature.com/nsu/981217/981217-1.html> (11 October 2002)
Google. <http://www.google.com/search?q=positronic> (11 October 2002)
Merrison, Jonathan Peter. "Atomic Collisions." Institut for Fysik og Astronomi Web Site. <http://www.phys.au.dk/~merrison/atomic_collisions.htm> (11 October 2002)
Mitroy, Jim. Researcher Profile. Northern Territory University Web Site. <http://www.ntu.edu.au/research/profiles/profile_mitroy.html> (11 October 2002)