Hospitals have very strict --- procedures in place in order to keep everything extremely clean.
sanitation
How dinosaurs went extinct is still a/an --- to paleontologists around the world.
enigma
That has to be your dad in that photo. You're the --- of him!
spitting image
That traditional children's story is a --- to warn children not to talk to strangers.
cautionary tale
An archeologist discovered a new chamber in an Egyptian pyramid after a strong --- that a room would be found there.
hunch
It is hard for me to believe that Hans is about to retire, but I'll ---
take your word for it
He's had such a/an --- with ancient cultures that she's now majoring in archelogy in college.
fascination