Apple’s lost a trademark dispute in China, meaning it may have to find a new name for the iPad if it wants to continue selling the device in the country.

A year ago, Apple launched two lawsuits against local monitor vendor Proview, which in 2001 registered ‘iPAD’ and ‘IPAD’ as its trademarks.

In 2009, the Taiwanese subsidiary of Proview sold the trademark to UK company IP Applications, which in turn sold them to Apple for about $55,000 the following year.

However, the Shenzhen Municipal Intermediate People’s Court has now decided that the transfer of the trademarks was not valid.

It was the Taiwanese subsidiary which carried out the sale, rather than the Chinese parent company which officially owned them – and that parent company, ruled the court, retained the right to use the trademarks on the Chinese mainland.

As a result, it says, the contract wasn’t binding there. Apple’s been ordered to pay costs.

Now, Proview has launched its own trademark infringement lawsuit against Apple, and is after $1.5 billion in compensation; Apple may have to pay up if it wants to contimu using its iconic iPad name.

Proview Shenzhen needs the cash: it’s reported to be on the brink of bankruptcy.

China is an extremely important market for Apple. It’s now the world’s largest smartphone market, and the iPhone is the biggest smartphone brand. It’s also the world’s largest PC market.

Apple’s been on a push to expand its retail presence in the company, and has signed deals with several telecoms firms. By 2014, says Morgan Stanley, the country’s expected to become Apple’s biggest market.