Male nipples are simply called nipples. There isn't a separate, distinct name for them. While the term "teat" is sometimes used to refer to nipples in non-human mammals (as noted in the Wikipedia snippet), it's not a common or appropriate term for human male nipples.
Why Do Men Have Nipples?
The presence of nipples in males is a result of embryonic development. During fetal development, the same tissues that form nipples in females also form in males. Because there's no evolutionary advantage for males to not have nipples, the trait persists. Some biologists even classify male nipples as a spandrel—a byproduct of evolutionary processes, not a trait directly selected for. (Reference: In male mammals)
The male nipple-areola complex (NAC), while lacking a physiological function in males like lactation, retains similar hormone sensitivity and sexual responsiveness as in females. (Reference: Diseases of the male nipple and areola). Men, like women, have nipples with numerous nerves that enhance sexual arousal (Reference: Breast Anatomy: Milk Ducts, Tissue, Conditions & Physiology).
It's important to note that while men typically cannot lactate, conditions such as gynecomastia (breast enlargement) and galactorrhea (nipple discharge) can occur. (References: The Reason Why Men Have Nipples, Why Do Men Have Nipples? 9 FAQs About Lactation, Pain, and More). Additionally, men can develop breast cancer, which often originates in the ducts leading to the nipple. (References: Male breast cancer - Symptoms and causes - Mayo Clinic, Breast cancer in men | NHS inform, Male Breast Cancer: Symptoms, Diagnosis & Treatment).
