His idealistic approach was inspiring, but some found his plans unrealistic.

idealistic 是由名词 ideal（理想）加上形容词后缀 -istic 构成的形容词。ideal 指"理想、完美的标准"，-istic 表示"具有...特性的"。idealistic 合起来表示"理想主义的"，指过分追求理想而可能忽视现实情况的态度或方法。