Which term derives from a greek word meaning “to speak with good words” and involves substituting a more pleasant, less objectionable way of saying something for a blunt or more direct way?

   Euphemism

Explanation:  Euphemism is a word that has a Greek root and means to replace some unpleasant or shameful word or expression with some milder, indirect expression or word. It is used instead of some harsh expression, most often, say, to replace the term dead, and so used passed away. However, sometimes it is not a good idea to use a euphemism to mitigate or mask the seriousness of the problem, such as when you say social drinker instead of  alcoholic.

i believe the answer is:   psychological  experiment

in this experiment, wilhelm wundt became the first person that implement scientific method in analyzing the pyschological phenomenon.

due to this result, wilhelm wundt also able to make psychology to be acknowledged as a separate scientific field from biology.

answer; allows decision to stand;