Define a generation.

I seem to remember Ms Sturgeon saying that the September 2014 referendum in Scotland was a "once in a generation event". "This probably is a once in a life time opportunity for Scotland".   

Yet only two years later on 13 October 2016 she announced that an Independence Referendum Bill would be published for consultation the following week.   

So did she tell a lie saying it was once in a generation event?  Or was she thinking in terms of the generation of a hamster, not a human?