O

obey - v. to act as one is ordered to act

object - v. to show that one does not like or approve; to protest; n. something not
alive that can be seen or touched?

observe - v. to watch; to look at carefully; to celebrate or honor something ("They
will observe the anniversary of the day she was born.")?

occupy - v. to take and hold or to control by force?

ocean - n. the area of salt water that covers almost seventy-five percent of the
earth’s surface; any of the five main divisions of this water?

of - prep. made from; belonging to; about; connected to; included among?

off - ad. away; at a distance; condition when something is no longer operating or
continuing; not on; not connected?

offensive - n. a military campaign of attack; ad. having to do with attacking?

offer - v. to present or propose; n. the act of presenting or proposing; that which is
presented or proposed?

office - n. a room or building where business or work is done; a public position to
which one is elected or appointed?

officer - n. a person in the military who commands others; any person who is a
member of a police force?

official - n. a person with power in an organization; a representative of an
organization or government; ad. of or about an office; approved by the government
or someone in power?

often - ad. many times?

oil - n. a thick liquid that does not mix with water and that burns easily; a black
liquid taken from the ground and used as fuel?

old - ad. not young or new; having lived or existed for many years?

on - prep. above and held up by; touching the upper surface of ("The book is on the
table."); supported by ("He is on his feet."); about ("The report on the meeting is
ready."); at the time of ("He left on Wednesday.")?

once - ad. one time only?

only - ad. being the single one or ones; no more than ("We have only two dollars.")?

open - v. to start ("They opened talks."); ad. not closed; not secret?

operate - v. to do work or a job; to cut into the body for medical reasons?

opinion - n. a belief based on one’s own ideas and thinking?

oppose - v. to be against; to fight against?

opposite - ad. different as possible; completely different from; exactly the other way
("North is the opposite direction from south.")?

oppress - v. to make others suffer; to control by the use of unjust and cruel force or
power?

or - conj. giving another of two choices; giving the last of several choices?

orbit - v. to travel in space around a planet or other object; n. the path or way an
object travels in space around another object or planet?

order - v. to give a command; to tell someone what to do; n. a command; the correct
or normal way things are organized; a peaceful situation in which people obey laws?

organize - v. to put in order; to put together into a system?

other - ad. different; of another kind; the remaining one or ones of two or more
("That man is short; the other is tall.")?

our - ad. of or belonging to us?

oust - v. to force to leave; to remove by force?

out - ad. away from the inside; opposite of in?

over - conj. above; covering; across， in or on every part of ("all over the world")?

overthrow - v. to remove from power; to defeat or end by force?

owe - v. to pay or have to repay (usually money) in return for something received?

own - v. to have or possess for oneself