The Ras element of the name literally means 'horn', but in this context would usually be taken as 'cape'. Morthil is more difficult to decipher, but almost certainly contains the root mor-, 'dark' or 'black'. The final -thil is far less certain, but is perhaps connected to til, another word for 'horn', giving a reduplicative name that translates as something like 'Cape Darkhorn'. Alternatively, morth means 'darkness' in the Book of Lost Tales, so the name may be something as simple as 'Cape Darkness' (though this source predates The Lord of the Rings by several decades, and its use of language may not be applicable in this context).