What does "gloom" mean?

Additional senses

1. 2.Cloudiness or heaviness of mind; melancholy; aspect of sorrow; low spirits; dullness. A sullen gloom and furious disorder prevailed by fits. Burke.
2. 3.In gunpowder manufacture, the drying oven. See Darkness.
3. 4.To shine or appear obscurely or imperfectly; to glimmer.
4. 5.To become dark or dim; to be or appear dismal, gloomy, or sad; to come to the evening twilight. The black gibbet glooms beside the way. Goldsmith. [This weary day] . . . at last I see it gloom. Spenser.
5. 6.To render gloomy or dark; to obscure; to darken. A bow window . . . gloomed with limes. Walpole. A black yew gloomed the stagnant air. Tennyson.
6. 7.To fill with gloom; to make sad, dismal, or sullen. Such a mood as that which lately gloomed Your fancy. Tennison. What sorrows gloomed that parting day. Goldsmith.