immature

形容词 immature:

1. characteristic of a lack of maturity
2. lacking in development
   同义词：unformed
3. (used of living things especially persons) in an early period of life or development or growth
   同义词：young
4. not fully developed or mature; not ripe
   同义词：green, unripe, unripened
5. not yet mature
6. (of birds) not yet having developed feathers
   同义词：unfledged

1. He pretends he's been around but he's really very immature.
   他装作老於世故，而实际上却很不成熟。
2. Not ripe or matured; immature.
   不成熟的未熟或成熟的; 不成熟的
3. Inexperienced, immature, or untried.
   无经验的、不成熟的或未经试验的
4. Silly, immature behavior.
   愚蠢的，不成熟的行为

im.ma.ture

adj.（形容词）
Not fully grown or developed.See Synonyms at young
未长成的，未充分发展的：生长或发展不完全的参见 young
Marked by or suggesting a lack of normal maturity:
不成熟的：以缺乏正常的成熟为标志的：
例句：
silly, immature behavior.
愚蠢的，不成熟的行为

来源：
Latin imm3tôrus
拉丁语 imm3tôrus
in- [not] * see in-
in- [不] *参见 in-
m3tôrus [mature] * see m3-
m3tôrus [成熟的] *参见 m3-

【引伸】
im.mature.ly
adv.（副词）
im.matur.ity 或
im.mature.ness
n.（名词）