What is Elegy and its origin?

Elegy: a poem of serious reflection, typically a lament for the dead.

The word elegy derives from the Greek élegos, "funeral lament.” It was among the first forms of the ancients, though in Greek literature it refers to a specific verse form as well as the emotions conveyed by it. Any poem using the particular meter of the elegiac couplet or elegiac distich was termed an elegy.