“Youth” has several meanings, but it often has an old-fashioned, condescending or almost literary feel to it. The more common term is young people, or more colloquially youngsters or (if appropriate) teenagers or even kids.
When I was still a student in England, it was a Young Persons Railcard, for example, not a Youth Railcard – that just sounds wrong.
- As an uncountable noun, youth refers to late childhood or young adulthood.
- As a countable noun, a youth always refers to a teenage lad. The dictionary definition allows girls too, but I don’t think I’ve ever heard it used that way in normal speech.
- As a collective noun, youth refers to e.g. a country’s young people.
- The adjectival use meaning “for young people” is unusual, but there are exceptions such as “youth hostel” – although that also has the feel of having originated as a transliteration of jeugdherberg or Jugendherberge.
There are some weird-sounding translations around from Dutch for bodies like the Youth Inspectorate. What? They go around inspecting young people? (At least the IGJ’s own official preference is for “youth care”.)
Prevalence: high. I’ve come across it particularly often in scientifically-oriented texts on criminality, education, health, travel, sex education and more.
Frequency: endemic. Anything with the Dutch jeugd in tends to get translated blindly as youth. Don’t.
Native: sort of. It’s a perfectly good word, of course, but it just tends to have that condescending, daddy-knows-best kind of overtone. Which is fine if that’s the nuance you want…