insubstantial

形容词 insubstantial:

1. lacking material form or substance; unreal
   同义词：unsubstantial, unreal
2. lacking in nutritive value
   同义词：jejune

1. Something unreal, insubstantial, or imaginary.
   幻想不真实，不实在，或被想象出来的某个事物
2. Early aircraft were insubstantial constructions of wood and glue.
   早期的飞行器是木头和胶粘合的脆弱机器。

in.sub.stan.tial

adj.（形容词）
Lacking substance or reality.See Synonyms at immaterial
缺乏实质或现实性的参见 immaterial

Not firm or solid; flimsy.
不坚固或不实在；脆弱的
Delicate; fine.
精致的；精美的

【引伸】
in.substan.tial.ity