Based on the results of the tests, I can attempt to describe the function f(x):

[DESCRIPTION]: The function f(x) tends to return a higher value (closer to 1) for words associated with abstract concepts (e.g. love, justice, light, darkness, anger), while returning lower values (closer to 0) for more concrete, tangible words (e.g. apple, dog, water, music). It seems to be selective for words related to emotions, values, and non-material elements.