The Greek origin of the word means "lover of children". For this reason it was appropriated by people with sexual urges towards children (although the Greek use is far broader and most often has no sexual connotations - for instance a "Russophile" can someone who likes to visit Russia or who supports Russian foreign policy). It has now become a descriptive or hostile term for such people.
Refers to child molesters and child rapists, as well as people who view sexual images of children and those who would like to do so. Current usage makes it unclear whether it is a sexual orientation or a class of actions.
Strictly speaking, it refers only to those interested in pre-pubescent children. (Attraction to teenagers is hebephilia).
All paedophile activities which involve actual children are forms of child abuse.