· ominous
· outside
· overwhelming
The word you're looking for is opaque.
optimism
Origin
Overcast is a weather word. It describes the sky when it is mostly covered by clouds.
ozone
The Maori word for talk starting with a "k" and ending with an "o" is "kōrero."
Summer = KAH-yeets (קיץ) winter = KHO-ref (חורף) summer or winter = o kah-yeets o kho-ref (או קיץ או חורף)
observantold-fashionedoutgoing
origin.
orgy
Outstanding
obscene