How many letters does the top answer for “formed with or like a rainbow.” have?

The most common answer is rainbowed (9 letters).

Crossword clue: formed with or like a rainbow.

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

rainbowed 9 letters web-def

an arc of colored light in the sky caused by refraction of the sun's rays by rain

formed like a bacillus 50% similar → bacillar, bacillary, bacilliform

formed like an obelisk. 50% similar → obeliscal

formed like of corn. 50% similar → graniform

formed like the nose. 50% similar → nariform