A generic trademark, also known as a proprietary eponym, is when a brand name becomes the word used for all products of that type. The best example being Hoover. Hoover is a brand of vacuum cleaner yet the majority of people call all vacuum cleaners Hoovers.
It's extremely difficult and probably impossible to actually define the moment a brand becomes generic as it tends to happen over quite a long period of time.
In general company's do everything they possibly can to stop their brands becoming generic, after all, why would Hoover want people calling a Dyson a Hoover? Google actively discourages the media from using the term 'googling' in an attempt to stop the trademark becoming generic.
In severe cases the original company can lose all IP Trademark rights meaning any company can then use their brand name. An example is the 'Philips head screw' which was originally a trademark that Henry Philips owned. Now any company can use the term 'Philips head screw'.
There are a number of demographics that seem to use the word 'iPad' for all tablets, in particular older people and those less technologically minded.
In work they've recently installed tablets at the the till points. I'm not entirely sure what brand they are but they're certainly not iPads. Despite this my (elderly-ish) boss calls them iPads, customers comment on them saying 'Cool, you're using iPads'. For Christmas my four year old, severely spoilt nephew had a 'Child Pad'. Nearly every member of my family, including my nephew, call it an iPad despite me telling them 'IT'S NOT AN IPAD!'.
So I don't think 'iPad' is a generic trademark just yet but I'm convinced that it soon will be unless Apple and other brands like Amazon and Google do something about it.
Do you know anybody that says 'iPad' for all tablets or do you know any other interesting generic trademarks? Comment below.