mutter

As nouns the difference between whistle and mutter

is that whistle is a device designed to be placed in the mouth in order, or driven by steam or otherwise, to make a whistling sound while mutter is .

As a verb whistle

is (ambitransitive) to make a shrill, high-pitched sound by forcing air through the mouth to produce a whistling sound, restrictions to the flow of air are created using the teeth, tongue and lips.

As a noun mutter

is .

As a verb knawvshawl is

(ireland) to mutter or complain sullenly.

As a noun mutter

is a repressed or obscure utterance; an instance of muttering.

As a verb mutter

is to utter words, especially complaints or angry expressions, indistinctly or with a low voice and lips partly closed; to say under one's breath.

As an adverb mutteringly is

with a muttering sound.