How many letters does the top answer for “make a buzzing sound” have?

The most common answer is bombinate (9 letters).

Crossword clue: make a buzzing sound

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

bombinate 9 letters wn-def

make a buzzing sound

buzz 4 letters wn-def

make a buzzing sound

a signaling device that makes a buzzing sound 60% similar → buzzer

in a buzzing manner; with a buzzing sound. 50% similar → buzzingly

make a crackling sound 50% similar → crackle, crepitate

make a murmuring sound 50% similar → purl, sough

make a rattling sound 50% similar → brattle, clatter

make a rhythmic sound 50% similar → thrum

make a strident sound 50% similar → blare, blast