Full Idea
Meinongian abstraction principles say that for any (suitably restricted) class of properties, there exists an abstract entity (arbitrary object, subsistent entity) that possesses just those properties.
Clarification
'abstraction principles' are for set formation
Gist of Idea
A Meinongian principle might say that there is an object for any modest class of properties
Source
Gideon Rosen (The Limits of Contingency [2006], 04)
Book Reference
'Identity and Modality', ed/tr. MacBride,Fraser [OUP 2006], p.20
A Reaction
This is 'Meinongian' because there will be an object which is circular and square. The nub of the idea presumably resides in what is meant by 'restricted'. An object possessing every conceivable property is, I guess, a step too far.