1. in a manner characterized by speaking in low, indistinct tones, often expressing discontent or complaint
Usage: formed from the verb 'mutter' with the adverbial suffix '-ingly'

Examples

• He walked away mutteringly, unhappy with the decision.
• She mutteringly complained about the long wait in line.
• The old man sat in the corner, mutteringly voicing his objections.
• He mutteringly agreed to help, though he clearly did not want to.
• The student mutteringly repeated the difficult instructions to herself.