Thanks for the replies. Sorry for not being more specific, I wrote my post pretty late. I assumed since I posted my question in the recording techniques forum, you guys would know that my question applies to recording.

My question should've read, "what is ad hoc and how does it relate to recording?"
I wasn't quite asking for definition, I thought it might've been an acronym or something. I didn't think of looking it up in a dictionary. I thought ad hoc was one of those buzz-jargon-lingo-words that gets used in recording talk that I never heard of. Reason why I asked, is that I came across this word in some magazine articles and posts I read on RAP.
Here are some of the usages I've seen:
"Although ADR is difficult with experienced actors and crew, it's even harder when you have to do it ad-hoc..." (BTW I do know what ADR is and what is stands for)
"P5-100's are marginal for doing digital recording under
ad-hoc setup and usage..."--discussing recording with computers
"this kind of use only occurs in old or ad hoc PA setups..."--discussing passive DI boxes.
"There was so much bleed between the ad hoc control room and the performance space..."
So....with the above examples what was meant by "ad hoc/ad-hoc?"
Thanks again guys.
--Haku