Imaginaries

Can anyone give me a definition of "imaginaries"?

I've just come across it in a book, and I recall coming across it in a
book I was editing a couple of years ago. I made enquiries at the
time, and thought I had made a not ofn it, but could not find my note.

A websearch only brought up somthing about the square root of -1, and
the contexts in which I have encountered it are not mathematical. 

It seems to be related to concept, conception, construction and
similar terms, and I would like to know how it differs from them in
its precise meaning. 

What would be the difference between, for example:

Concepts like X
and 
Imaginaries like X

???



-- 
Steve Hayes from Tshwane, South Africa
Web:  http://www.khanya.org.za/stevesig.htm
Blog: http://methodius.blogspot.com
E-mail - see web page, or parse: shayes at dunelm full stop org full stop uk