MedGen

Central precocious puberty for which no underlying cause can be identified. [from NCI]

Premature development of the breasts. [from HPO]

Central precocious puberty (CPP), also referred to as gonadotropin dependent precocious puberty, is an endocrine-related developmental disease characterized by the onset of pubertal changes, with development of secondary sexual characteristics and accelerated growth and bone maturation, before the normal age of puberty (8 years in girls and 9 years in boys). [from ORDO]

The onset of secondary sexual characteristics before a normal age. Although it is difficult to define normal age ranges because of the marked variation with which puberty begins in normal children, precocious puberty can be defined as the onset of puberty before the age of 8 years in girls or 9 years in boys. [from HPO]