'Nobility' is an English word, not a Polish word.
Actually, it is derived from Latin/French.
Being szlachta had much more to do with Freedom than responsibility - as one poster said 'Golden Freedon'.
You misconceive the relationship, in the Polish context, between freedoms and responsibilities. The szlachta, per se, did not seek to hamstring the imposition of responsibilites purely by virtue of the fact that they wished more 'freedom'. The freedom aspect to Constitutional policy during the Cth. had more to do with limiting absolutist, arbitrary and despotic rule of a king. They saw and foreshadowed what would happen to the Cth (as happened in England) if they allowed themselves (like the Brits) to be taken over by "Royalty". It was the Freedom to have a voice and a guiding hand in how you were governed. Sometimes the partnership worked well (Bathory), other times it didn't (Wettin).
The paramount responsibility of the szlachta (or nobility) was that of protecting Poland, or Pospolite Ruszenie, the levee en masse. Freedom and responsibility were not mutually exclusive mind you - for example; in the C15, certain 'privileges' were agreed upon for the szlachta, and given by the King, one of which was the obligation of Pospolite Ruszenie being limited to actions inside Poland. Thus, the szlachta sought to limit the King's ability to issue the call to arms and prevent involvement in the disputes of other countries.
This is why Freemen is a much better English translation.
Sorry, but it's not - a dicto simpliciter ad dictum secundum quid. It would be like saying that a frog has skin, and because humans have skin, we must be frogs too.
But can you say the Polish Freemen always had a high social standing?
You ought to be disabused of your misconception. Whether you like it or not, szlachta were nobles. Sorry, but you can't change that. I would suggest a perusal of Lukowski's "Liberty's Folly". It is in depth, though elementary, and you will find it easy to understand. Relying on Carlyle will not allow an understanding of the nuances of Polish nobility and Constitutional Law.
Unfortunately as with all forms of anarchy, the powerful (i.e. the true nobility) flourished at the expense of others
You again misconceive and misrepresent the legal/constitutional concept of unanimity with anarchy. Please refrain from sniping and being disingenuous.
For example, the Liberum veto was not so stupid, as some believe.
Exactly (it's good to see someone who seems to understand it). The Liberum Veto was the purest form of democracy (I acknowledge its applicability to the szlachta however). It was not an object to which failings could be ascribed. The only failing of the Polish body politic was not legislating contingency protocols for what was to happen if the Liberum Veto was enacted, and such enaction hamstrung the passing of other legislation.
To blame the Liberum Veto as some sort of vehicle for 'anarchy' is simply wrong because it is illogical, when you really sit down and think about it.
For your information, the political system of I RP was Noble Democracy,
Indeed it was. At the time, it was a stupendous victory for unanimity and consent over unilateral, arbitrary despotism.