Definition of "property"

[Irv Kalb]

I am doing some writing (for an upcoming book on OOP), and I'm a little stuck.  

I understand what a "property" is, how it is used and the benefits, but apparently my explanation hasn't made the light bulb go on for my editor.  The editor is asking for a definition of property.  I've looked at many articles on line and a number of books, and I haven't found an appropriate one yet.

I have written some good examples of how it works, but I agree that a definition up front would be helpful.  I have tried a number of times, but my attempts to define it have not been clear.  Perhaps the best I've found so far is from the Python documentation:  

A property object has getter, setter, and deleter methods usable as decorators that create a copy of the property with the corresponding accessor function set to the decorated function. 

But I'm hoping that someone here can give me a more concise (one or two sentence) definition of the word "property".   

(I would like to avoid going through the whole derivation with the property function, as that would distract from the points that I am trying to make.) 

Thanks in advance,

Irv