Definition from Wiktionary, the free dictionary
Displaced native Old English unwemmed (“pure, untainted”).
- Having no stain or blemish; spotless, undefiled, clear, pure.
- Were but my soul as pure From other guilt as that, Heaven did not hold One more immaculate. — Sir John Denham
- Thou sheer, immaculate and silver fountain. — Shakespeare, Richard II, V-iii.
Derived terms 
having no stain or blemish, spotless, undefiled, clear, pure
- vocative masculine singular of immaculātus