[n] excessive sadness and mournfulness [n] a feeling of melancholy apprehension [n] an atmosphere of depression and melancholy; "gloom pervaded the office"
gloom, gloom, glumness, lugubriousness, somberness
ambiance, ambience, apprehension, apprehensiveness, atmosphere, bleakness, desolation, dread, melancholy, uncheerfulness
bleakness, cynicism, darkness, defeatism, dismalness, dreariness, gloom, gloomy outlook, gravity, grimness, lower, lowering, malism, negativism, nihilism, pessimism, retreatism, solemnity, somber, somberness, sombrousness, uncheerfulness, wearifulness, we
\Gloom"i*ness\, n. State of being gloomy. --Addison.