loss of male virginity
Specifically refers to a male losing his virginity. Often used in contrast with 処女喪失 (loss of female virginity).
See also: 処女喪失
He lost his virginity at age twenty.
Refers to loss of female virginity, while 童貞喪失 is specifically for males.
Compound of 童貞 (male virginity) and 喪失 (loss).