"Integrated Development Environment", basically a fancy editor with a whole in-memory database behind it (it builds up a data structure representing your code, so it can use it to do code assist/completion, pop up javadoc, quickly find all references to a given method or field or class name, etc.).
Somewhere I read someone's good essays, on the Web (try Google) about the concept of "SCID", which all good IDE's do now.... SCID stands for "Source Code In Database".