Finding suitable synonyms for the word "unnervingly" can be a challenging task, but it is essential to add variety and richness to your writing. Some possible alternatives to consider include disturbingly, unsettlingly, disconcertingly, unsettling, jarring, alarming, creepy, eerie, spine-chilling, hair-raising, unsetting, and unnerving. Each of these synonyms conveys a sense of unease or discomfort, but they differ in the particular feeling they evoke. Therefore, it's crucial to choose the best synonym based on the message you want to convey and the tone of your writing. With the right synonym, you can make your writing more descriptive and engaging.