Funerals are lugubrious. So are rainy days and Mondays.

Lugubrious comes from the Latin verb lūgēre, “to mourn.” You can also listen to the sound of the word: lugubrious sounds slow, heavy, and sad. Sometimes, just the “feel” of a word is enough to clue you in to its meaning, and lugubrious is one of those words. I was feeling great when I got to the concert, but the lugubrious music left me in a terrible mood.