noun, Psychiatry. 1. an inability to speak, due to a physical defect, conscious refusal, or psychogenic inhibition. Origin of mutism.
1 A new study finds girls are developing breasts earlier than ever before; American boys and girls are entering puberty about five years younger than they did in 1920.
Girls usually complete puberty by ages 15â17, while boys usually complete puberty by ages 16â17. The major landmark of puberty for females is menarche, the onset of menstruation, which occurs on average between ages 12â13; for males, it is the first ejaculation, which occurs on average at age 13.or most boys, puberty takes about six years and ends when they are about 17 or 18 years old. At the end of puberty, a teenager is usually about 10 to 30 centimetres (cm) (4 to 12 inches (in)) taller, 7 to 29 kilograms (kg) (15 to 65 pounds (lb)) heavier, and stronger.