/am"euh noyd'/ , n.
any cephalopod mollusk of the extinct order Ammonoidea, from the Devonian to the Cretaceous periods, having a coiled, chambered shell.
[ 1880-85; Ammonoidea, equiv. to Ammon ( ites ) name of the order + -oidea -OIDEA; see AMMONITE 2 ]