Which word ends with ff?

The correct answer is: Scoff

The most frequent double letter combinations are ee, ll, ss, oo, tt, ff, rr, nn,pp, and cc. The double letters that occur most commonly at the end of words are ee, ll, ss, and ff. There is two words 'scoff' and 'water'. But the word 'scoff' has only double letter. So, the word 'scoff' ends with 'ff'.