IPA: /ˈɡlʌməst/
KK: /ɡlʌmɪst/
The most sad or gloomy; feeling or showing a lack of hope or cheerfulness.
After hearing the bad news, he looked the glummest he had ever been.
Comparative: glummer
Superlative: glummest
Glummest is derived from "glum" (from Old Norse "glumr", meaning gloomy or sullen) and the superlative suffix "-est" (meaning most). The word "glummest" refers to the state of being the most gloomy or sullen.
Think of the Old Norse word for gloomy, 'glumr', to remember that 'glummest' means the most gloomy.