What is the crossword answer for the clue: Humming sound

WHIR - a 4 letter word may be the answer you are looking for!

WHIRR - a 5 letter word may be the answer you are looking for!

DRONE - a 5 letter word may be the answer you are looking for!

SING - a 4 letter word may be the answer you are looking for!

BIRR - a 4 letter word may be the answer you are looking for!

BUZZ - a 4 letter word may be the answer you are looking for!

Humming sound

4 Character Answers:

BIRR

BUZZ

SING

WHIR

5 Character Answers:

DRONE

WHIRR