De- (?).
A prefix from Latin de down, from, away; as in debark, decline, decease, deduct, decamp. In words from the French it is equivalent to Latin dis- apart, away; or sometimes to de. Cf. Dis-. It is negative and opposite in derange, deform, destroy, etc. It is intensive in deprave, despoil, declare, desolate, etc.
© Webster 1913.