Superlative form of glum; the most sad, quiet, or melancholy.
From 'glum' + '-est' (superlative suffix). The '-est' suffix derives from Old English and Indo-European roots, used to form the highest degree of comparison.
The superlative 'glummest' was famously used in literature to describe the most depressed characters—it's become shorthand in English for hitting rock bottom emotionally.
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