How many letters does the top answer for “of a bright red or purple color.” have?

The most common answer is puniceous (9 letters).

Crossword clue: of a bright red or purple color.

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

puniceous 9 letters web-def

Of a bright red or purple color. [R.]

punicial 8 letters web-def

Of a bright red or purple color. [R.]

of a purple color; purple. 50% similar → purpureal