meaning of NRI as per ITA, 1961

Yes. Refer Section 6(4) and 6(6) of the ITA.  It says any person......that means, as long as the entity qualifies as a person in the ITA Section 2 definition, it can be decided that it is a Resident/Non-Resident by virtue of Section 6.

If a person is does not fulfill requirement of being a "resident" as per Section 6(4), in my view, it can be inferred that it is a "Non Resident"

If a person is does not fulfill requirement of being a "resident" as per Section 6(4), in my view, it can be inferred that it is a "Non Resident"