In the past, the Scouts was called the Boy Scouts.
He was in the Boy Scouts.
2. countable noun
A Boy Scout was a boy who was a member of the Boy Scouts.
boy scout in British English
noun
1. Scout
2. US and Canadian informal
an apparently virtuous and innocent person
Boy Scout in American English
1.
a member of the Boy Scouts, a worldwide boys' organization, founded in England (1908), that stresses character, citizenship, outdoor life, and service to others; specif., a member of the division of Boy Scouts of America (1910) for boys eleven to seventeen years of age