noun

1. behavior or thought based on a conception of things as they should be or as one would wish them to be; idealization
2. a striving to achieve one's ideals
3. imaginative treatment in art that seeks to show the artist's or author's conception of perfection; representation of imagined types, or ideals
4. Philos. any of various theories which hold that:
   1. things exist only as ideas in the mind rather than as material objects independent of the mind
   2. things in the material world are actually manifestations of an independent realm of unchanging, immaterial models or forms

Etymology: Fr idéalisme or Ger idealismus