What is “torture”?

A question for Vox Nova readers and bloggers:  What is “torture”?  Let’s put aside, for present purposes, any definitions of the term that might be provided in particular legal texts.  I can look those up.  What I want to know is, if the question is posed, “is ____ torture?”, what would be the characteristics of “____” that would indicate that it is, or is not, “torture”?

In asking this, I am assuming (and, of course, believe) that “torture” is immoral (i.e., not morally justifiable on consequentialist grounds).  I am also assuming (hoping?) that readers understand and believe that I have no partisan or snarky purpose in asking the question.  I really want to know what people think it is that distinguishes “torture” from permissible ways of getting people to do or say things that they would not otherwise want to do or say (e.g., “unless you tell us who your accomplice was, we will prosecute you for a higher-grade offense”).