NW - now
NX - narthex
NY - navy
NZ = nertz
OA = ocarina
OB = outclimb
OC - A very bad TV show.
Oh, all right: obec (the Czech and Slovak word for a municipality)
OD - overdosed
OE = office
OF - off
OG- oolong
OH - ostrich (or Oshkosh)
OI - octopi
OJ - OJ (as in orange juice)
OK: oink
OL = optical
OM = optimism
ON - Omicron
OO- oregano
OP = outcrop