Most people I talk to tend to think "normal = majority". In the recent campaign for (against) same-sex partnerships in Switzerland, normal was whatever the bible said (even for people who never read it nor believe in any religion).
And for myself? I don't know (at least, excluding the mathematical/geometrical meaning). I can't come up with a list of what I consider normal or not...
2 a : according with, constituting, or not deviating from a norm, rule, or principle b : conforming to a type, standard, or regular pattern