Green’s Dictionary of Slang

(US campus) a newcomer, a novice.

1972		Eble Campus Sl. Oct. 4: Newk—beginner, novice.
1985		Roskey Muffled Shots 45: In the U.S. Army Pacific, ... replacements were called variously ‘newks,’ ‘newbies,’ or ‘mugs’ [HDAS].