A person aged 18 or over who feels lust towards the mini Canadian.
My sister is 29 and she told me she had a sex dream about Justin Beiber she is for sure a Beiberfile
A younger person (under the age of 16) crushing on someone much older then them. Usually a bieber fan, aged between 4-12 who wants to marry Justin Bieber who is nearly twice their age.
John: Oh my God That girl is such a beiberfile
Jane: I know right he's nearly twice her age.