Answer:

birrs

Answer	Crossword Clue
BIRRS	Whirring sounds
BIRRS	Currency of Ethiopia
BIRRS	Fluttering sounds

BIRRS	Whirs.
BIRRS	Whirring sounds.
BIRRS	Whirrs.
BIRRS	Vibrant whirring sounds

Crossword

a puzzle consisting of a grid of squares and blanks into which words crossing vertically and horizontally are written according to clues.