adverb, adverb taking the 'to' particle
naggingly; gripingly; in a scolding manner
Describes the manner of complaining, scolding, or nagging persistently and loudly. Often used with 言う or similar verbs.
母は私にガミガミ言った。
My mother nagged at me.
上司がガミガミと文句を言う。
The boss complains gripingly.