pederasty: literally, boy love. Pederasty in the modern sense usually refers to an erotic relationship between an adult and a teenager.
The term is based on the ancient Greek custom of older men mentoring adolescent youths from Greek, pais, boy + erastes, lover. It is not a synonym for pedophilia, though it is considered by many as analogous with ephebophilia.
Pederasty is the most common form of male same-sex love and sexuality. Besides its practice in Ancient Greece where it was sanctioned by the state and the religion, and it required the consent of the youth as well as that of his father, similar age-structured relationships formed a pattern of homosexual relationships which, with some variations, can be found in Japanese, Chinese, Central Asian, Middle Eastern, North African, and Iberian cultures.