O
obey v
object n
observe v
* obtain
* obvious a
* occupation n
occupy v
* occur v
ocean n
Oceania n
of prep
off prep & ad
* offence n
offer n&v
office n
officer n
official n&a
offshore a
often ad
* oilfield n
O. K. ad
old a
Olympic(s) a&n
on prep &ad
once n, ad &conj
one pron
oneself pro
n
onion n
only a &ad
onto prep
open a&v
opening n
Opera n
operate v
operation n
operator n
opinion n
* oppose v
opposite n&a
optimistic a
* optional a
or conj
oral a
orange n & a
* orbit n
order n& v
ordinary a
* organ n
organise (Am organize) v
organization n
* origin n
other pron & a
otherwise ad
ought modal v
our pron
ours pron
ourselves pron
out ad
* outcome n
outdoors ad
outer a
outgoing a
outing n
* outline n
* output n
outside n, ad & prep
* outspoken a
* outstanding a
* outward(s) ad
* oval n & ad
over prep & ad
overcoat n
overcome v
* overhead a
* overlook v
* overweight a
* owe v
own a & v
owner n
* ownership n
ox (pl oxen) n
oxygen n