How many letters does the top answer for “an organism that thrives in a relatively acid environment” have?

The most common answer is acidophil (9 letters).

Crossword clue: an organism that thrives in a relatively acid environment

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

acidophil 9 letters wn-def

an organism that thrives in a relatively acid environment

acidophile 10 letters wn-def

an organism that thrives in a relatively acid environment