The function seems to be computing the sum of the ASCII values of characters in the input string and then converting the sum to its corresponding English word.

[CODE]:
```
def ascii_sum_to_word(input_str):
    num2words = {1: 'one', 2: 'two', 3: 'three', 4: 'four', 5: 'five', 6: 'six', 7: 'seven', 8: 'eight', 9: 'nine',
                 10: 'ten', 11: 'eleven', 12: 'twelve', 13: 'thirteen', 14: 'fourteen', 15: 'fifteen', 16: 'sixteen',
                 17: 'seventeen', 18: 'eighteen', 19: 'nineteen', 20: 'twenty'}

    ascii_sum = sum(ord(c) for c in input_str)
    return num2words.get(ascii_sum, 'undefined')
```