1) Bounceable 2) Deficiency 3) Dependent by virtue of youth 4) Like some collegians 5) Like someone using a fake ID 6) Minor 7) Nonaged 8) Not 21 in some cases 9) Not of legal age 10) Not old enough 11) Not yet legal 12) Shortfall 13) Too young for a draft 14) Using a fake id Found on https://www.crosswordclues.com/clue/underage