Threnody
Etymology
From Greek "thrēnōidia," combining "thrēnos" (a lament, dirge) and "ōidē" (song, ode). The same "-ody" element sits inside melody, parody, and rhapsody.
noun · /THREN-uh-dee/
A song, poem, or speech of lamentation for the dead.
What it names
A precise, sonorous word for a formal work of mourning — useful when "sad song" is too plain for something composed deliberately as a lament.
Example
Penderecki’s "Threnody to the Victims of Hiroshima" makes the strings themselves keen with grief.
Related idea
Narrower than an elegy, which is a broadly mournful, reflective poem; a threnody is specifically a lament for the dead, closer to a sung dirge.