Breast development, early
The beginning of breast development at puberty is known medically as thelarche.
It is now a normal event at an earlier age (e.g., age 8) than in the past.
The term thelarche comes from two Greek words: 'thele,' nipple + 'arche,' beginning.
Thelarche is frequently (and incorrectly) written without the 'h' as telarche.