chicken-and-egg
adjective
chick·en-and-egg ˈchi-kᵊn-ən(d)-ˈeg 
-ˈāg
: of, relating to, or being a cause-and-effect dilemma
Word History
Etymology
from the proverbial question "which came first, the chicken or the egg?"
First Known Use
1857, in the meaning defined above