IPA: /ˈɡlʌmli/
KK: /ɡlʌmli/
In a way that shows sadness or disappointment.
He looked glumly at the ground after hearing the bad news.
Glumly is derived from the adjective 'glum' (of uncertain origin, possibly from Old Norse 'glumr', meaning gloomy or sullen) combined with the adverbial suffix '-ly' (meaning in a manner of). The word 'glumly' describes the manner of being gloomy or sullen.
Think of someone acting in a 'gloomy' way ('glum') and remember that 'glumly' means to do so in a gloomy manner.