From Wiktionary, the free dictionary
From co- + chief.
co-chief (plural co-chiefs)
- Alternative form of cochief
2024 December 28, Jonathan Nicholson, “Yes, There Are Ways To Cut The Budget Deficit. 'DOGE' Hasn’t Found Them So Far.”, in HuffPost[1]:That’s not what President-elect Donald Trump, who appointed Musk and Ramaswamy as co-chiefs of the advisory panel, has planned.