'deconvert' originates from the Latin prefix 'de' (Latin 'de') meaning 'away, off', combined with 'convert' ultimately from Latin 'convertere', where 'con-' meant 'together' and 'vertere' meant 'to turn'.

'deconvert' is a modern English formation by adding the prefix 'de-' to 'convert' (from Old French 'convertir' and Latin 'convertere'); the specific verb 'deconvert' appears as a 20th/21st-century coinage rather than an inherited medieval English word.

The root 'convert' historically carried the sense 'to turn together/around' and came to mean 'change (especially belief)'; 'deconvert' extends the prefix sense 'away/off' to mean 'undo that conversion' — either to reverse a technical conversion or to reverse a religious conversion (i.e., cause loss of belief).