- K or klicks – kilometer.
- KA-BAR – fighting/utility knife first issued during World War II.
- keeper – cloth loop on the green service blouse to hold the cloth belt neatly in place.
- kelly helmet or K-pot – 1917-model basin helmet worn during World War I until 1942.
- kevlar – helmet made from kevlar.
- keyboard jockey – person whose job causes him or her use a computer for a length of time.
- kill hat – a junior Drill Instructor who specializes in discipline and punishment. See also heavy hat.
- Kuni – Marine Corps Air Station Iwakuni.
Read more about this topic: List Of United States Marine Corps Acronyms And Expressions