is a Latin word (from the words lucem ferre), literally meaning "light-bearer", which in that language is used as a name for the dawn appearance of the planet Venus, heralding daylight. Use of the word in this sense is uncommon in English, in which "Day Star" or "Morning Star" are more common expressions.
In English, "Lucifer" generally refers to Satan, although the name is not applied to him in the New Testament. The use of the name "Lucifer" in reference to a fallen angel stems from an interpretation of Isaiah 14:3"20, a passage that speaks of a particular Babylonian King, to whom it gives the title of "Day Star", "Morning Star" (in Latin, lucifer), as fallen or destined to fall from the heavens or sky. In 2 Peter 1:19 and elsewhere, the same Latin word lucifer is used to refer to the Morning Star, with no relation to the devil. However, in post-New Testament times the Latin word Lucifer has often been used as a name for the devil, both in religious writing and in fiction.