noun
male high school student; boys' high school student
Refers to a male student attending high school. The two English gloss are essentially synonymous; 'boys' high school student' can imply a student at an all-boys school, but in practice the term is used broadly for any male high schooler.
あの男子高生は毎朝早く起きて勉強している。
That male high school student wakes up early every morning to study.
駅で男子高生たちが楽しそうに話していた。
Some male high school students were chatting happily at the station.
Compound of 男子 (だんし, 'male') + 高生 (こうせい), an abbreviation of 高校生 (こうこうせい, 'high school student').