impractical

形容词 impractical:

1. not practical; not workable or not given to practical matters
2. not practical or realizable; speculative
   同义词：airy, visionary, Laputan, windy

1. One who is unrealistic and impractical; a visionary.
   空想家不现实和不实际的人; 幻想者
2. The plan is feasible in reason but impractical.
   这个计划道理上行得通，但不现实。
3. The ideals or principles of a utopian; idealistic and impractical social theory.
   乌托邦思想及理论空想社会主义者的理想或原则; 理想但不切实际的社会主义学说

im.prac.ti.cal

adj.（形容词）
Unwise to implement or maintain in practice:
不切实际的；不现实的：不明智地坚持或实行的：
例句：
Refloating the sunken ship proved impractical because of the great expense.
打捞沉船由于费用巨大而显得不切实际

Incapable of dealing efficiently with practical matters, especially finances.
不实用的：不能有效处理实际事务的，特别是对财政事务
Not a part of experience, fact, or practice; theoretical.
理论的：不属于经验、事实或实际的；理论上的
Impracticable.See Usage Note at impracticable
行不通的参见 impracticable

【引伸】
imprac.tical.ity