Of, relating to, or characteristic of an elegy; mournful, sorrowful, or expressing lamentation in the manner of elegiac verse.
From elegy (Greek elegeia) plus the adjective suffix -ious (from Latin -iosus). This creates an adjective meaning 'full of or characterized by' the quality of elegies or mourning.
Elegious is an older variant of elegiac—it's the kind of word Victorian writers used when they wanted to sound extra literary and sad, like the atmosphere of a fog-shrouded cemetery.
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