Economics. *sigh* Just another field that HAS to use words in idiosyncratic ways in order to attempt to make its jargon less acceptable to the hoi polloi. Example: in common speech “rival” and “competitor” are synonyms. In Economics, however, a good (yeh, another one, but with strong etymological roots) is rival if its use or consumption by one party denies another party its use or consumption.
Fugetaboutit.