Grindingly is an adverb that describes an action or situation that is difficult, unpleasant, and takes a lot of time to accomplish. There are several synonyms for the word grindingly, including laboriously, painfully, wearisomely, and agonizingly. Laboriously refers to a task that requires a lot of physical effort. Painfully implies something that causes physical or emotional pain. Wearisomely describes something that is tiring and boring to do. Agonizingly implies something that is highly distressing or painful. Other synonyms for grindingly include lethargically, sluggishly, and ponderously, which indicate a slow and tedious pace. In summary, using a synonym for grindingly can add color and depth to a piece of writing, helping to convey the intended meaning more clearly.