Source : Webster's Revised Unabridged Dictionary (1913)

Glum \Glum\, n. [See {Gloom}.]
   Sullenness. [Obs.] --Skelton.

Glum \Glum\, a.
   Moody; silent; sullen.

         I frighten people by my glun face.       --Thackeray.

Glum \Glum\, v. i.
   To look sullen; to be of a sour countenance; to be glum.
   [Obs.] --Hawes.

Source : WordNet®

glum
     adj 1: reflecting gloom; "gloomy faces" [syn: {gloomy}, {long-faced}]
     2: showing a brooding ill humor; "a dark scowl"; "the
        proverbially dour New England Puritan"; "a glum, hopeless
        shrug"; "he sat in moody silence"; "a morose and
        unsociable manner"; "a saturnine, almost misanthropic
        young genius"- Bruce Bliven; "a sour temper"; "a sullen
        crowd" [syn: {dark}, {dour}, {glowering}, {moody}, {morose},
         {saturnine}, {sour}, {sullen}]
     [also: {glummest}, {glummer}]