How many letters does the top answer for “mercilessness characterized by a lack of pity” have?

The most common answer is pitilessness (12 letters).

Crossword clue: mercilessness characterized by a lack of pity

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

pitilessness 12 letters wn-def

mercilessness characterized by a lack of pity

ruthlessness 12 letters wn-def

mercilessness characterized by a lack of pity