Based on the results from all three tests, it seems like the function f(x) assigns higher values to words with abstract concepts and lower values to more concrete concepts. Some words with multiple meanings might also be considered abstract since they may be linked to broader concepts. Imperfectly, the function could be described as follows:

[DESCRIPTION]: The function appears to evaluate the degree of abstractness of a given word. Words associated with more abstract concepts have values closer to 1, whereas more concrete words have values closer to 0.