The function takes a string input and returns the length of the input string as a word (e.g., "apple" -> "five").

[CODE]:
```python
def string_length_as_word(s):
    length_words = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve"]
    return length_words[len(s)]
```