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

The most common answer is hadean (6 letters).

Crossword clue: another word for plutonian

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

hadean 6 letters gen-syn

the earliest eon in the history of the Earth from the first accretion of planetary material (around 4,600 million years

tartarean 9 letters gen-syn

of or relating to or characteristic of Hades or Tartarus

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