There are 'ghost words' which have become established. E.g. _derring-do_: "The two words _durring_, _dorryng_, _daring_, verbal noun from _durran_, _dorren_ "t

There are 'ghost words' which have become established. E.g. _derring-do_: "The two words _durring_, _dorryng_, _daring_, verbal noun from _durran_, _dorren_ "to dare" v.1, and _don_, _do_, present infinitive of "do" v., literally "daring to do", which, by a chain of misunderstandings and errors, have come to be treated as a kind of substantive combination, taken to mean, Daring action or feats, ‘desperate courage’. The words come incidentally in their ordinary sense and construction followed by the object ‘that’ (= what, that which) in Chaucer's Troylus; whence, in an imitative passage by Lydgate, in an absolute construction more liable to misunderstanding; Lydgate's _dorryng do_ was misprinted in the 16th cent. editions (1513 and 1555) _derrynge do_, in which form it was picked up by Spenser and misconstrued as a substantive phrase, explained in the Glossary to the Sheph. Cal. as ‘manhood and chevalrie’. Modern romantic writers, led by Sir W. Scott, have taken it from Spenser, printed it _derring-do_, and accentuated the erroneous use." (from the OED)