What is the accurate term to refer to the government of India that sits in New Delhi and forms, along with the states and local bodies, the...

What is the accurate term to refer to the government of India that sits in New Delhi and forms, along with the states and local bodies, the Indian state?
Popularly – and often even in official communication – the institution is called the “Central government”. Or even just the Centre for short. However, Tamil Nadu’s ruling party insists that the correct term is actually the “Union government”.
So what’s the right view?
Why are we discussing it now? And why are there so many terms anyway?
How did this controversy start?
Ever since the new DMK government assumed office on May 7, official statements and press releases have carried the Tamil term “Ondriya Arasu” to refer to the Union government. Earlier, the preferred term in state government communication seems to have been “Maththiya Arasu” or Central government.
The DMK has justified the change to “Ondriya Arasu” as reflecting the correct constitutional position. According to its leaders, the Constitution describes India as a “Union of States” and therefore the ideal reference to the Centre would be the “Union Government”.
The Bharatiya Janata Party in Tamil Nadu has been vocal against the DMK government’s use of “Ondriya Arasu” in official communication, with some of its spokespersons claiming that they were suspicious about the DMK’s sudden...