Alphabetical List - O

An) old fox is not easily snared.	A person of experience is difficult to fool or manipulate.
Once bitten, twice shy.	After an unpleasant experience, people are careful to avoid something similar.
One father is (worth) more than a hundred schoolmasters.	A teacher cannot replace a father. A child is raised by a father and taught by a teacher.
One good turn deserves another.	You should be helpful to someone who helps you.
One of these days is none of these days.	Until a date is set, 'one of these days' remains a vague promise.
One today is worth two tomorrows.	What you have today is better than what is promised or hoped for.
One man's meat is another man's poison.	People don't always like the same things.
One man's trash is another man's treasure.	What is useless to one person could be valuable to another.
One swallow doesn't make a summer.	A single satisfactory event does not mean that all the others will be as good.
(An) onion a day keeps everyone away.	A humoristic version of "an apple a day..."
Only real friends will tell you when  your face is dirty.	Only a real friend will tell you the truth.
Opportunity seldom knocks twice.	Don't miss opportunities that come along.
(An) ounce of discretion is worth a pound of wit.	It is better to be cautious and discreet than to try to be funny.
(An) ounce of prevention is worth a pound of cure.	It is easier to prevent something from happening than to repair the damage or cure the disease later.
Out of the mouth of babes and sucklings.	Children often speak wisely.
Out of sight, out of mind.	We tend to forget people or things that we do not see.