The function f(x) seems to be selective for concepts related to celestial bodies, specifically the sun, moon, mercury, and possibly other planets. These words are associated with higher values closer to 1. Other words like apple, banana, cat, dog, elephant, math, history, and science have lower values closer to 0. This suggests that the function is discriminating between words related to celestial bodies and other categories. Although there may be other concepts that the function is selective for, the strongest association appears to be with celestial bodies.