Gynecomastia is an endocrine system disorder in which a noncancerous increase in the size of male breast tissue occurs. Wikipedia

See also

• breasts - Tag for fully developed breasts.
• busty_boy_(lore) - If full-on breasts but the character is otherwise fully male, tag this.
• moobs - Non-breast fat tissue in males located where breasts typically would be.
• pecs - Excessive muscle tissue in males located where breasts typically would be.