How many letters does the top answer for “another word for treacherous” have?

The most common answer is perfidious (10 letters).

Crossword clue: another word for treacherous

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

perfidious 10 letters gen-syn

tending to betray; especially having a treacherous character as attributed to the Carthaginians by the Romans

punic 5 letters gen-syn

the Phoenician dialect of ancient Carthage

another word for about 50% similar → approximately, roughly, some

another word for terms 50% similar → footing

another word for under 50% similar → nether

another word for word 50% similar → phrase