Refers to a young person, often in legal or formal contexts where age matters (e.g., labor laws, age restrictions).
This facility restricts use by minors.
There are special regulations for the employment of young people.
若者 is a common, neutral word for 'young person' or 'youth', while 年少者 is more formal and often used in legal or official contexts.
Compound of 年少 (young, underage) + 者 (person). The exact historical derivation is uncertain, but the word follows a standard Sino-Japanese pattern.