decuman
adjective
dec·u·man
ˈdekyəmən
1
of a wave : extremely large : huge
that decuman wave that took us fore and aft
P. A. Motteux
P. A. Motteux2
: of or relating to the tenth cohort —used especially of the chief gate of a Roman camp
Word History
Etymology
Latin decumanus, decimanus of the tenth, large, from decumus, decimus tenth (from decem ten) + -anus -an