The Collaborative International Dictionary of English v.0.48:

Adolescent \Ad`o*les"cent\ ([a^]d`[-o]*l[e^]s"sent), a. [L.
   adolescens, p. pr. of adolescere to grow up to; ad + the
   inchoative olescere to grow: cf. F. adolescent. See Adult.]
   Growing; advancing from childhood to maturity.
   [1913 Webster]

         Schools, unless discipline were doubly strong,
         Detain their adolescent charge too long. --Cowper.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Adolescent \Ad`o*les"cent\, n.
   A youth.
   [1913 Webster]

WordNet (r) 3.0 (2006):

adolescent
    adj 1: relating to or peculiar to or suggestive of an
           adolescent; "adolescent problems"
    2: being of the age 13 through 19; "teenage mothers"; "the teen
       years" [syn: adolescent, teen, teenage, teenaged]
    3: displaying or suggesting a lack of maturity; "adolescent
       insecurity"; "jejune responses to our problems"; "their
       behavior was juvenile"; "puerile jokes" [syn: adolescent,
       jejune, juvenile, puerile]
    4: in the state of development between puberty and maturity;
       "adolescent boys and girls"
    n 1: a juvenile between the onset of puberty and maturity [syn:
         adolescent, stripling, teenager, teen]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "adolescent":
   at half cock, baby, callow, fledgling, green, half-baked,
   half-cocked, half-grown, hopeful, ill-digested, immature, impubic,
   infant, junior, juvenal, juvenile, maturescent, minor, nubile,
   pubescent, raw, sapling, slip, sprig, stripling, teenager, teener,
   teenybopper, underripe, unfledged, ungrown, unmellowed, unripe,
   unseasoned, young hopeful, young person, younger, youngest,
   youngling, youngster, youth