The etymology of the phrase "3rd world country"[1] is interesting, and isn't directly related to economic strength. According to the original definition, India is indeed a 3rd world country.
A second definition of 3rd world is "developing countries" [2]. India still falls into this definition, but it's rapidly approaching "developed country" status.
I have read these articles before. But these definitions are from a different time and have an unnecessary stigma attached to them (How did non aligned countries end up meaning poor ?).
I don't think India is a developed (what does this even mean anymore) country, nor will it be one in the near future. But I think calling one of the largest economies (4th in PPP, 9th in nominal gdp) as third world a bit simplistic..
Thats funny because there are so many third world countries, with higher per capita incomes, better infrastructure and far better legal systems than India.
My point is that there are third world countries (and they are universally regarded so) which are better than India in a lot of respects. I am indian, I have travelled to some of the other third world countries and have seen it myself.
So basically, India is not even the better one among third world countries.
You just called India a 3rd world country ? sigh