Boyd’s Bible Dictionary:
The crowing of the cock (Matt. 26:34; Mark 14:30; Luke 22:34), indicated the third watch of the night, from midnight to daylight.
Concise Bible Dictionary:
Mentioned only in connection with the denial of Peter (Matt. 26:34,74-75); and with the “cock crowing,” a division of time at which the Lord may come (Mark 13:35): this corresponds to the third watch of the night, and would be about 3 o’clock, A. M.
Strong’s Dictionary of Greek Words:
Meaning:
from ἀλέκω (to ward off); a cock or male fowl