Specifically in Christian contexts, referring to the fallen angel.
In Christianity, Lucifer is considered a fallen angel.
Extended use: a devilish or demonic figure, not necessarily the biblical Lucifer.
The morning star is also called Lucifer.
He has a devilish charm, almost like Lucifer.
明けの明星 is the plain Japanese term for the morning star (Venus), while ルシファー is a more poetic, Latin-derived name for the same phenomenon.
天使 means angel, the heavenly counterpart to ルシファー, who is the fallen angel turned devil.
堕天使 is the general term for any fallen angel, while ルシファー is the specific named figure most famously identified as one.
From English 'Lucifer', ultimately from Latin 'lucifer' meaning 'light-bringer'.