• big, grown, developed, experienced, old, mature, adult.

Synonyms for Immature:

• adj.

  •all (adjective)
  • immature.
  •early (adjective)
  • soonest.
  •green (adjective)
  • wet behind the ears,
  • Unconversant,
  • bosky,
  • Undecayed,
  • growing,
  • half-formed,
  • verduous,
  • undried,
  • foliate,
  • ungrown.
  •imperfect (adjective)
  • inexact,
  • few bugs,
  • bottom of barrel,
  • warped,
  • two bit,
  • lemon,
  • bottom-of-barrel,
  • junker,
  • minus.
  •incomplete (adjective)
  • Unexecuted,
  • unconsummated,
  • partial,
  • discontinuous,
  • half-done,
  • short,
  • undone,
  • half done,
  • Curtailed,
  • unsatisfactory,
  • under construction,
  • Unaccomplished,
  • insufficient,
  • patchy,
  • lacking,
  • fractional,
  • unattained,
  • deficient,
  • incomplete,
  • segmental,
  • unachieved,
  • missing,
  • scanty,
  • Parter,
  • sectional,
  • unfulfilled,
  • fragmentary.
  •juvenile (adjective)
  • young,
  • unweaned,
  • milk-fed,
  • kiddish,
  • beardless.
  •latent (adjective)
  • suspended,
  • implied,
  • between the lines,
  • in abeyance,
  • unrealized,
  • vestigial.
  •little (adjective)
  • tiny,
  • shrimpy,
  • least,
  • under-sized,
  • not large,
  • mini,
  • not big,
  • smallish,
  • hardly any,
  • Toyer,
  • wee,
  • snubber.
  •Other relevant words: (adjective)
  • unfixed,
  • dependent,
  • germinal,
  • weak,
  • found wanting,
  • latent,
  • unfinished,
  • unwrought,
  • tottering,
  • Kidder,
  • pendent,
  • prentice,
  • insecure,
  • imperfect,
  • nascent,
  • nitwitted,
  • crude,
  • trustful,
  • predeveloped,
  • the latest,
  • spring chicken,
  • out-standing,
  • unsettled,
  • just out,
  • Neoteric,
  • irresponsible,
  • unpasteurized,
  • Infantine,
  • Fluctuant,
  • unassembled,
  • rootless,
  • premature,
  • rash,
  • in the rough,
  • inchoate,
  • unseasoned,
  • rudimentary,
  • in the making,
  • unfamiliar with,
  • babylike,
  • open to attack,
  • ungraded,
  • this season's,
  • Unmilled,
  • unwise,
  • unanswerable,
  • up for grabs,
  • emptyheaded,
  • wet behind ears,
  • unworked,
  • unshielded,
  • raw,
  • fresh,
  • hot off press,
  • pre-adult,
  • under thumb,
  • betwixt and between,
  • undercooked,
  • what's happening,
  • uncareful,
  • developmental,
  • Unbaked,
  • uninitiate,
  • unproficient,
  • Unsustaining,
  • just begun,
  • unsorted,
  • unconcluded,
  • overearly,
  • sheepheaded,
  • in firm,
  • unanticipated,
  • tied to apron strings.
  •rash (adjective)
  • overhasty,
  • head-strong,
  • unconsidered,
  • Insuppressible,
  • over hasty,
  • jumping to conclusions,
  • precipitant.
  •rudimentary (adjective)
  • nuts-and-bolts,
  • uncompleted.
  •small (adjective)
  • pint-sized,
  • shrimper,
  • runty,
  • shrimp,
  • small-scale,
  • bitty,
  • pocket-sized.
  •tottery (adjective)
  • tottery.
  •unprocessed (adjective)
  • unprocessed.
  •untried (adjective)
  • untried,
  • Unattempted,
  • Unexpert,
  • unproved.
  •weak (adjective)
  • forceless,
  • weakest.
  •young (adjective)
  • child-like,
  • blooming.
  •young, inexperienced (adjective)
  • tenderfoot,
  • kid,
  • KIDSTUFF,
  • unseasonable,
  • untimely,
  • Undergrown.

• adv

  •early (adverb)
  • far ahead,
  • in the bud,
  • too soon,
  • Oversoon,
  • in time,
  • on the dot,
  • in bud,
  • before long,
  • with time to spare,
  • a bit previous,
  • on short notice,
  • in good time,
  • bright and early,
  • in advance.

• n.

  •
  • crazy,
  • not in your right mind/not right in the head,
  • ridiculous,
  • mad,
  • over-the-top,
  • laughable,
  • silly,
  • insane,
  • ludicrous.
  •immature (noun)
  • childish,
  • underdeveloped,
  • puerile,
  • embryonal,
  • infantile,
  • preadolescent,
  • boylike,
  • infant,
  • unfeathered,
  • pubescent,
  • preteen,
  • unfledged,
  • little,
  • undeveloped,
  • girlish,
  • early,
  • prepubescent,
  • unaged,
  • childly,
  • adolescent,
  • larval,
  • pupal,
  • youthful,
  • babyish,
  • teenage,
  • puppylike,
  • vulnerable,
  • juvenile,
  • schoolboyish,
  • green,
  • jejune,
  • naive,
  • vernal,
  • inchoative,
  • unsophisticated,
  • callow,
  • boyish,
  • prepubertal,
  • tender,
  • youngish,
  • small,
  • teen,
  • inexperienced,
  • newborn,
  • embryonic,
  • formative,
  • childlike,
  • prepupal,
  • junior,
  • puppyish,
  • schoolgirlish,
  • baby,
  • teenaged,
  • unformed,
  • unripe,
  • unripened.
  •Other relevant words: (noun)
  • potential.
  •youthful (noun)
  • half-grown,
  • Sophomoric.

• v.

  •defeated (verb)
  • unsuccessful.

• Other synonyms:

  •
  • full-blown.
  •
  • maturity,
  • full-fledged.
  •
  • plane.
  •
  • growth.
  •
  • pitch.