When you speak or act idealistically, you do it from high standards and a picture of how the world should be, even if that picture cannot really be reached. A new teacher may talk idealistically about every child loving school. A friend may plan a city idealistically, as if wanting fairness were the same as building it. The word is a little formal. In a café people more often say “in an idealistic way,” or they just call the person idealistic and leave the adverb alone. Newspapers still like it, often with a small sigh — decent, but not quite on the ground. Though actually, it is not the same as ideally. Ideally means “in the best case, if nothing goes wrong.” You can plan a trip ideally (cheap, fast, sunny) and still not be thinking idealistically at all.