How many letters does the top answer for “an order of birds, including the pigeons.” have?

The most common answer is columbae (8 letters).

Crossword clue: an order of birds, including the pigeons.

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

columbae 8 letters web-def

type genus of the Columbidae: typical pigeons

a division of birds including the true pigeons. 50% similar → gemitores

an order of birds including only the penguins. 50% similar → ptilopteri

an order of birds, including the genus apteryx. 50% similar → apteryges