1) one who sweeps and cleans a temple
2) one who has charge of a temple, to keep and adorn it, a sacristan
3) the worshipper of a deity
3a) word appears from coins still extant, it was an honourary title [temple-keeper or temple-warden] of certain cities, especially in Asia Minor, or in which some special worship of some deity or even some deified human ruler had been established; used of Ephesus
Part of Speech: noun masculine
From a form of G3485 and κορέω koreô (to sweep); a temple servant, that is, (by implication) a votary: - worshipper.
These two sites give similar information, with the definition from several dictionaries and statistics on the use of the word.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root νεωκόρος; click on the second column to search for that grammatical form of the root νεωκόρος; click on the third column to search for that word and grammatical form; click on the total to search for the root νεωκόρος.