aAntelucanHeld or being before light; -- a word applied to assemblies of Christians, in ancient times of persecution, held before light in the morning."Antelucan worship."
Century Dictionary and Cyclopedia
antelucanOccurring before daylight; preceding the dawn. Specifically applied to assemblies of Christians held in ancient times before daylight, at first to escape persecution, and afterward from motives of devotion or convenience.
Chambers's Twentieth Century Dictionary
adjAntelucanan-te-lōō′kan before dawn or daylight.