As per the definition of Steve Blank - a startup is a company that is yet to get profitable. Often such companies are under 3 years of running age. Most of the startups are either waiting to get acquired or they are waiting to get sell their product. And startup has now divided into multiple types, for example, startup that requires funding for it's initial growth called as VC funded startups, startups that are born from the shoestring budget of founder known as bootstrapped startup, and then there is non funded non bootstrapped startup which are formed from collective efforts of founders.
Startup word was first introduced in 1997. The days when the dotcom websites and products were in boom. After the dotcom websites crashing, the word stayed back. After 2007's economical crash, the startup word gained traction.
These days the word is overused and almost every type of "entrepreneurial" effort is called as "startup. For example photographer posting images on 500px and facebook page, is a startup. People being a freelancer and trying to establish a brand are also referred as startup. Some of the startups such as snapdeal, flipkart and shopclues artificially boost their value by showing public engagement, such startups which develop themselves for buyout are called unicorns. Usually any startup waiting to get acquired for their market disruptive idea is in this category. Such acquisitions are often full of loss and are just meant to lure investors.
There are no fixed set of qualities. However if your company profit exceeds the expenses and also remains consistent with revenue then it loses the name of "startup". And then it becomes the real business.
Traditional business go for the profit and customer acquisition from day one. However startups are often inflating themselves with more of show than chasing the profit. For example, selling candy on road is traditional business, it's less glamorous. Selling candy online becomes startup and hype.
In India, the way the startups are viewed and have gained traction is completely different than the startups in other countries.
