IPA: //ʌn.fʊlˈfɪl.ɪŋ//
KK: /ʌnˈfʊlfɪlɪŋ/
Not providing a sense of satisfaction or achievement; disappointing.
Many people find their jobs unfulfilling when they do not feel challenged or appreciated.
Unfulfilling → It is formed from "un-" (meaning not) and "fulfilling" (from the root "full" meaning filled and the suffix "-ing" indicating the action of). The word describes something that does not provide a sense of fullness or satisfaction.
Think of 'not' ('un-') providing a sense of 'fullness' ('fulfilling') — that's why unfulfilling means something that does not satisfy.