coc ‧ cyx /ˈkɒksɪks $ ˈkɑːk-/ BrE AmE noun ( plural coccyxes or coccyges /kɒkˈsaɪdʒiːz $ ˈkɑːksə-/) [countable] technical
[ Date: 1500-1600 ; Language: Modern Latin ; Origin: Greek kokkyx 'cuckoo' ; because it looks like a cuckoo's beak ]
the small bone at the bottom of your ↑ spine SYN tailbone