dí​gu

apprehensive

嘀咕 dí​gu
apprehensive verb
to feel uneasy, suspicious, or worried about something

His words left me full of misgivings.

mutter verb
to speak in a low, quiet voice, often to grumble or whisper privately

They were whispering something in the corner.

Frequency

Movie subtitles
1.25 per million appears in 1% of films
Written text
3.63 per million

Sources

Definitions
CC-CEDICT