What is Grutter?
1.
1. verb - to grumble and mutter simultaneously.
2. verb - to incomprehensibly express displeasure vocally.
"Dang kids and their stupid cell phones", the unhappy codger gruttered.
The vocal expression which is gruttered is called a "grutterance".
See
2.
a grutter, some one who 'gruts' is found to be extemely ugly.
did you see that utter grutter?
man, she gruts.
those bunch of females are grutting.