The name Drengist is never directly translated from Elvish to English, and indeed its Elvish etymology remains unclear. In notes reproduced in volume IV of The History of Middle-earth, however, Tolkien does provide an equivalent name in Old English. This is nearufléot, where nearu means 'narrow' and fléot is an 'estuary' or 'firth'. This term appears as part of a list of Elvish names and Old English intepretations, and it must be said that many of these are not direct translations. We can't therefore be sure that Drengist literally means 'narrow firth', but this is the closest we have to a translation of the name.