Thread:GalaxyGourmet/@comment-44011155-20191027175756/@comment-38078079-20191027180613

A legal minor; typically someone under eighteen.

It would depend on the context, though, as - for example - someone "underage" on this site would be in reference to laws on what details can be held on minors, so under 16 for the European area and under 13 for the rest of the globe.