How many letters does the top answer for “inhumaneness evidenced by an unwillingness to be kind or forgiving” have?

The most common answer is mercilessness (13 letters).

Crossword clue: inhumaneness evidenced by an unwillingness to be kind or forgiving

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

mercilessness 13 letters wn-def

inhumaneness evidenced by an unwillingness to be kind or forgiving

unmercifulness 14 letters wn-def

inhumaneness evidenced by an unwillingness to be kind or forgiving