Based on the function output for the given inputs, it seems like the function implemented by f(x) may be selective for emotions. The words "love", "fear", "happiness", and "sadness" have higher values compared to other words, indicating a stronger association with the concept of emotions. Other words like "cat", "dog", "tree", "apple", "banana", "water", "fire", "diamond", and "rock" have lower values, indicating a weaker association with emotions. 

Therefore, the description of the function f(x) could be: 

[DESCRIPTION]: The function f(x) measures the level of association of a word with the concept of emotions, where a higher value indicates a stronger association with emotions.