The function takes a string input and returns the word representing the length of the input string.

[CODE]:
```python
def string_length_word(s):
    number_words = {0: "zero", 1: "one", 2: "two", 3: "three", 4: "four", 5: "five", 6: "six", 7: "seven", 8: "eight", 9: "nine", 10: "ten"}
    return number_words[len(s)]
```