Answer:

mutters

Answer	Crossword Clue
MUTTERS	Grumbles quietly
MUTTERS	Indistinct utterances.
MUTTERS	Grumbles.

MUTTERS	Grumbles, sotto voce.
MUTTERS	Growls
MUTTERS	Speaks indistinctly
MUTTERS	Complains
MUTTERS	Complains sotto voce
MUTTERS	Says "You no-good son of a ...," say

Crossword

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