What term describes a male's first ejaculation of semen?

The term that describes a male's first ejaculation of semen is "spermarche." This event signifies the onset of male fertility and is an important milestone in male reproductive development, similar to how menarche marks the start of menstruation in females. Spermarche usually occurs during the early teenage years, typically between ages 11 and 15, although this can vary depending on individual development.

Menarche refers specifically to a female's first menstrual cycle, thus it's not applicable in this context. Puberty is a broader term that encompasses the overall process of physical changes that occur during adolescence, including both spermarche and menarche, but does not specifically denote the event itself. Initiation, while it might suggest the beginning of a phase or process, lacks the specificity needed to accurately describe this particular milestone in male sexual development. Thus, spermarche is the precise term used to denote this significant event.