Something that is insubstantial is not large, solid, or strong.
例句
Mars has an insubstantial atmosphere, consisting almost entirely of carbon dioxide...火星的大气层极其稀薄,几乎全部由二氧化碳构成。Her limbs were insubstantial, almost transparent.她的四肢非常纤细,几乎是透明的。
英汉词典释义
adj.
非实在的
an insubstantial semblance不实在的表象an insubstantial mirage on the horizon地平线上虚幻的海市蜃楼
英英词典释义
Adjective
1. lacking material form or substance; unreal;
"as insubstantial as a dream""an insubstantial mirage on the horizon"