ODLING, (?) "must have some relation to tricking and cheating" (Nares).
OMINOUS, deadly, fatal.
ONCE, at once; for good and all; used also for additional emphasis.
ONLY, pre-eminent, special.
OPEN, make public; expound.
OPPILATION, obstruction.
OPPONE, oppose.
OPPOSITE, antagonist.
OPPRESS, suppress.
ORIGINOUS, native.