IPA: /ʌnˈnɜːrvɪŋli/
KK: /ʌnˈnɜrvɪŋli/
In a way that causes anxiety or discomfort; to a disturbing extent.
The movie was unnervingly realistic, making the audience feel uneasy.
Unnervingly → It is formed from "un-" (meaning not) and "nervous" (from Latin "nervosus", meaning sinewy or vigorous) and the suffix "-ly" (meaning in a manner of). The word describes something that is not just nervous but does so in a manner that is unsettling or disturbing.
Think of 'not' ('un-') being combined with 'nervous' to describe something that makes you feel uneasy or disturbed.