How many letters does the top answer for “a device for changing one substance or form or state into another” have?

The most common answer is converter (9 letters).

Crossword clue: a device for changing one substance or form or state into another

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

converter 9 letters wn-def

a device for changing one substance or form or state into another

convertor 9 letters wn-def

a device for changing one substance or form or state into another