f(x) is a function that takes a word input and returns a value between 0 and 1, indicating the degree of association between the input word and a particular concept. The function is selective for words related to geography, literature, nature, and science and technology. It has a strong association with words that refer to bodies of water, such as "Lake Superior" and "Lake Huron," and with words related to the outdoors and nature, such as "series" and "nest." The function also appears to have some association with words related to science and technology, such as "chemistry" and "CPU."