antiseptic- something used to kill germs; free of germs

antisocial- unable to associate with other people; not sociable

contradiction- a statement that is opposite to another statement

counterbalance- a weight used to balance another weight; to balance or offset

counterproductive- producing the opposite of what is desired or intended

oblique- not straight; slanting, inclined, or sloping

obnoxious- very unpleasant and objectionable

obscure- to make unclear; to conceal or make less obvious

obstinate- unyielding; unreasonably determined to have one's own way