open letter
A public message in the form of a letter addressed to a particular person or to a group.
There was an open letter to the president of the United States in today's morning paper.
open market
Goods or securities available for purchase by all.
The stocks of certain companies are on the open market.
open marriage
An arrangement by mutual agreement between husband and wife whereby they are both allowed to have extramarital affairs.
Chances are the open marriage arrangement they had didn't work out too well so they are getting a divorce.
open one's eyes
open up one's eyes
To make a person see or understand the truth; make a person realize; tell a person what is really happening or what really exists.
Mary didn't believe that her cousin could be mean until the cousin opened Mary's eyes by scratching and biting her.
John's eyes were opened up to the world of nature when he visited his grandfather's farm.
open one's heart
To talk about your feelings honestly; confide in someone.
After going around worrying, Mary opened her heart to her mother.
John felt much better after he opened his heart to Betty.
To be sympathetic to; give love or help generously.
Mrs. Smith opened her heart to the poor little boy.
After the moving speech by the UN official, the people opened their hearts to the poor people of India.
open onto
To have a view of.
Our apartment in Chicago has a set of windows that open onto Lake Michigan.
open question
A debatable issue.
Whether assisted suicide is legal and moral or not is still an open question, recent publicity on the matter notwithstanding.
open secret
Something that is supposed to be a secret but that everyone knows.
It is an open secret that Mary and John are engaged.
Who will be appointed as the next president of the college is an open secret.