Something that is lost or has perished; a thing that no longer exists or survives.
From Latin deperditus (lost, ruined) plus -ite (a suffix used in various scientific and philosophical terms). This is a variant formation related to deperdit, using the noun-forming -ite suffix.
The word 'deperdite' is so rare it barely appears in modern English, but medieval scholars treasured it as a technical term for the catastrophic losses of classical literature during the Dark Ages—thousands of texts simply ceased to exist.
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