It's neither negative nor positive. It's Latin for "manner of working" and merely means "the manner in which a particular person performs a certain task".
You'll usually use it in reference to criminals. For example, a criminal might knock on the door of elderly people, pretend to be from the telephone company and, while "inspecting the wires", look to see if there is anything of value; and if there is, he breaks in two or three nights later. That would be his "modus operandi" (or "M.O." for short), and if several people are robbed in the same way, that's a good indication that it might be the same criminal at work.
But anyone can have a modus operandi for anything they do regularly.
Both Rewboss and MrPedantic are right.
The Latin phrase "modus operandi" means "method of operating" [Rewboss wrote a very good explanation ] and I know it very well because my native language which is of Latin origin uses it very frequently : mod de operare [Romanian]--modus operandi [Latin]
Re: What does 'modus operandi' mean? (advanced question)
Originally Posted by piangel
Thanks for your answering. I guess I should post the entire sentence.
"The suggestion of XXX effectively is an admission by the authors of a fundamental change in the modus operandi." (XXX means some kind of method)
Above sentence is extracted from the reviewer's comment about my paper. I don't really know what that does mean.
If 'modus operandi' is usually used in criminal activity, does that imply that the reviewer thought I have done something bad?
with best regards,
"Modus operandi" is most commonly used in investigating criminal activity as you said, but not only.
"Modus operandi" means method or way of operating; manner or mode of operating
MO - an unvarying or habitual method of procedure
"The suggestion of XXX effectively is an admission by the authors of a fundamental change in the modus operandi." (xxx means...of a fundamental change in the method or way of operating)
"If 'modus operandi' is usually used in criminal activity, does that imply that the reviewer thought I have done something bad?" - the answer is : he[the reviewer as you say] states your way of operating or the method of procedure used by you. If you were involved in a criminal activity and you are guilty in the eyes of legal authorities , then , yes, you have done something wrong, and they want to state how you did it, the way you did it.
For further information see also : http://en.wikipedia.org/wiki/Modus_operandi