Primary amenorrhea is a form of amenorrhea, so lack of menstrual bleeding. It is called primary amenorrhea when a girl did not get her first period by the age of 16.
Sources:
- Mayo Clinic: Amenorrhea: https://www.mayoclinic.org/diseases-conditions/amenorrhea/symptoms-causes/syc-20369299 (accessed 27. July 2020)
- NIH: Eunice Kennedy Shriver National Institute of Child Health and Human Development. Amenorrhea: https://www.nichd.nih.gov/health/topics/amenorrhea (accessed 27. July 2020)
- Cleveland Clinic: Amenorrhea: https://my.clevelandclinic.org/health/diseases/3924-amenorrhea (accessed 27. July 2020)