If you describe a plan or idea as utopian, you are criticizing it because it is unrealistic and shows a belief that things can be improved much more than is possible.
例句
He was pursuing a utopian dream of world prosperity...他懷揣著一個實現世界繁榮的烏托邦之夢。A complete absence of national border controls is as utopian today as the vision of world government.在今天，完全取消國家邊界控制的觀點與建立一個世界政府的想法一樣不切實際。
ADJ
（政治或宗教思想）空想的，烏托邦式的
Utopian is used to describe political or religious philosophies which claim that it is possible to build a new and perfect society in which everyone is happy.
例句
His was a utopian vision of nature in its purest form.他對大自然懷有一種極為純粹的烏托邦式看法。
英漢詞典釋義
adj.
空想社會主義的;空想的,不切實際的
the great utopian dream that they have cherished for so long他們長期抱有的偉大的烏托邦式的夢想
n.
空想的社會主義者;空想家
His ideas on equality are viewed as utopian in the current political climate.在當前的政治氣候下，他關于平等的觀點被認為是烏托邦。
英英詞典釋義
Adjective
1. characterized by or aspiring to impracticable perfection;
"the dim utopian future""utopian idealists""recognized the utopian nature of his hopes"