"O"

OBAMA
OBTRUSIVE
OCEAN/sea
OCCUPY-Wall-Street
OCTOPUS
ODD
OF
OFFICE
OFFICIAL
OFTEN
OH-GEE
OH-I-SEE
OKAY
OLD
OLYMPICS
ON/[OFF]
ONCE
ONLY, SOMETHING]
OPEN
OPPOSITE-[across from, allergic, agree, disagree, STRUGGLE]
OR
ORDER
ORANGE
order-[see ANSWER]
ordinary-[see REGULAR, see NORMAL]
ORGAN
OTHER
OUNCE
OUR-[also see POSSESSION]
OUT - also see [see IN]
OUTSIDE
OVEN
OVER-[across, cross]
OWE-[bill, due, debt]
OWN
OWL