The term 'missing portion of text' can be described as a LACUNA, which is a six-letter word. A LACUNA is a gap or missing part in a manuscript, inscription, text, painting, or other document. It can also refer to a missing part of a musical composition or a missing link in a chain of evidence. Lacunae can be caused by damage to the original document, or by intentional or unintentional omission. In some cases, lacunae can be filled in with conjectural or hypothetical reconstructions.