Micropenis is a medical term that describes an unusually small penis in a human male.
A common criterion is a dorsal (measured on top) erect penile length at least 2.5 standard deviations smaller than the mean penis size . The condition is usually recognized shortly after birth. The term is most often used medically when the rest of the penis, scrotum, and perineum is well-formed, without ambiguity such as hypospadias.