IPA: /ˈnɪɡlɪŋ/
KK: /ˈnɪɡlɪŋ/
Describing something that is bothersome or annoying, often in a small or petty way.
She found the niggling doubts in her mind hard to ignore.
Niggling → The word originates from the Middle English 'niggle', which is a frequentative form of 'nig', meaning to fuss or to be overly concerned with trivial matters. The term conveys a sense of persistent worry or annoyance over small details.
Think of someone who is overly concerned with tiny details, fussing about them — that's what 'niggling' means.