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also known as

Known by another name or description. Often abbreviated "AKA" or "a.k.a." both in speech and in writing. The Affordable Care Act, also known as "Obamacare," came into effect in 2014.
See also: also, known

(if the) truth be known

I must admit; to be honest; in actuality. Truth be known, even though I majored in English literature, I've never read anything by Hemingway! I know I said I wanted to go out to the bars tonight, but if the truth be known, I'd rather just stay home and watch a movie.
See also: known, truth

let it be known

1. (literally) To make something public knowledge. She's letting it be known that she is single and ready to start dating again.
2. (by extension) An expression used to assert that something is true, especially in the face of criticism or distrust. I realize that many people here believe that my company has exploited its employees, but let it be known that we have never in our 50-year history done anything that would knowingly cause harm to our workers.
See also: known, let

if the truth were known

Prov. if people knew how something really was, instead of how it appears to be. If the truth were known, people wouldn't shop at that store. Its owners aren't as honest as they seem. Sam: You're always polite to Fred, but you don't really like him, do you? Alan: Well, no, if the truth were known.
See also: if, known, truth

knew it was coming

 and (had) known it was coming
to have expected in advance that something was to happen. I shouldn't act surprised. I knew it was coming. It's his own fault. He should have known it was coming.
See also: coming, knew

known fact

something that is generally recognized as a fact. That grass is green is a known fact. It is a known fact that John was in Chicago on the night of the murder.
See also: fact, known

known quantity

someone whose character, personality, and behavior are recognized and understood. We need not worry about how John will behave. He is a known quantity. Lisa is a known quantity and I am sure she will not surprise us by voting with the opposition.
See also: known, quantity

man is known by the company he keeps

Prov. A person tends to associate with people who are like him or her. Son, when you go away to school, spend your time with serious people; don't hang around with people who go to parties all the time. A man is known by the company he keeps. If you want to know what kind of person George is, look at his friends. A man is known by the company he keeps.
See also: company, he, keep, known, man

tree is known by its fruit

Prov. People judge your character by what you do. (Biblical.) The politician may say she believes in more spending on child care, but the tree is known by its fruit; she hasn't voted for a single measure that would help.
See also: fruit, known, tree

for reasons best known to himself (or herself, etc.)

used when recounting someone's behaviour to suggest that it is puzzling or perverse. chiefly humorous
See also: himself, known, reason

for a/some reason/reasons best known to himˈself, herˈself, etc.

(humorous) for a reason or reasons which other people find hard to understand: For reasons best known to himself, he wears two pairs of socks.
See also: known, reason

have seen/known better ˈdays

be in a worse condition than in the past: That jacket of yours has seen better days — isn’t it time you bought a new one?
See also: better, days, have, known, seen

let it be ˈknown/make it ˈknown that...

(formal) make sure that people are informed about something, especially by getting somebody else to tell them: The President has let it be known that he does not intend to run for election again.
See also: known, let, make

make yourself ˈknown to somebody

introduce yourself to somebody: I made myself known to the hotel manager.
See also: known, make, somebody

if (the) ˌtruth be ˈknown/ˈtold

used to tell somebody the true facts about a situation, especially when these are not known by other people: None of the students really liked the new teacher. In fact, if the truth be told, everyone was rather afraid of him.
See also: if, known, told, truth
References in classic literature ?
said Lord Wilmore, with that tone which is only known to natives of Great Britain.
I think you spoke of having known Mr Elliot many years?
It must have been about the same time that he became known to my father and sister.
She was obliged to recollect that her seeing the letter was a violation of the laws of honour, that no one ought to be judged or to be known by such testimonies, that no private correspondence could bear the eye of others, before she could recover calmness enough to return the letter which she had been meditating over, and say--
Yes," said Anne, "you tell me nothing which does not accord with what I have known, or could imagine.
They had previously known embarrassments enough to try the friendship of their friends, and to prove that Mr Elliot's had better not be tried; but it was not till his death that the wretched state of his affairs was fully known.
Nastasia Phillpovna's family name is Barashkoff--I know, you see-and she is a very well known lady, indeed, and comes of a good family, too.
It was a wretched thing for a mother thus to see her own son, a handsome, comely young gentleman in flourishing circumstances, and durst not make herself known to him, and durst not take any notice of him.
This was news too good for me to make light of, and, you may be sure, filled my heart with a thousand thoughts, what course I should take, how, and when, and in what manner I should make myself known, or whether I should ever make myself know or no.
I told him I was troubled because I found we must shift our quarters and alter our scheme of settling, for that I found I should be known if I stayed in that part of the country; for that my mother being dead, several of my relations were come into that part where we then was, and that I must either discover myself to them, which in our present circumstances was not proper on many accounts, or remove; and which to do I knew not, and that this it was that made me so melancholy and so thoughtful.
He joined with me in this, that it was by no means proper for me to make myself known to anybody in the circumstances in which we then were; and therefore he told me he would be willing to remove to any other part of the country, or even to any other country if I thought fit.
I therefore considered of going to Caroline, which is the only southern colony of the English on the continent of America, and hither I proposed to go; and the rather because I might with great ease come from thence at any time, when it might be proper to inquire after my mother's effects, and to make myself known enough to demand them.
Then he goes into the country besides, to think about making sketches; and in all places where there are visitors, he has a large acquaintance and is very well known.
I have often dreamed of myself as back there, seeing faces in the yard little known, and which I should have thought I had quite forgotten; but, as often as not, I have been abroad here--in Switzerland, or France, or Italy-- somewhere where we have been--yet always as that little child.
He told me that as he had no consecrated chapel, nor proper things for the office, I should see he would do it in a manner that I should not know by it that he was a Roman Catholic myself, if I had not known it before; and so he did; for saying only some words over to himself in Latin, which I could not understand, he poured a whole dishful of water upon the woman's head, pronouncing in French, very loud, "Mary" (which was the name her husband desired me to give her, for I was her godfather), "I baptize thee in the name of the Father, and of the Son, and of the Holy Ghost;" so that none could know anything by it what religion he was of.