A dirge is a song of mourning, performed as a memorial to someone who’s died. As you might imagine, a dirge is usually quite sad. Another word with a similar meaning that you might know is “requiem.”
The noun dirge comes from the Latin dirige, which means “direct,” and is the beginning of a prayer that translates as “Direct my way in your sight, O Lord my God.” Dirge can still have a religious meaning, but it can also be any sad and mournful song, poem, or hymn composed or performed in memory of someone who has died. You can also say that something mournful sounds like a dirge, using the word in a more poetic sense.