Q: sore losers とはどういう意味ですか?
A: It means people who can't be courteous about losing, who become resentful.
Q: "back a loser" mean ?
for example : No one wants to back a loser. とはどういう意味ですか?
A: @senator20220 I cannot think of any other meaning it would have.

I would not consider "back a loser" a proverb, either. Proverbs are older phrases and usually come from folk tales that teach a lesson. Like "Two wrongs don't make a right" or "The pen is mightier than the sword."
Q: So you're going to turn loser on me? とはどういう意味ですか?
A: Ah, I see.

It's not a grammatically correct sentence, but in other words she is saying "So now you're going to act like a loser?"

By the way, that was slang that I don't hear that much at all, so it shouldn't worry you at all.

Hope this helps! :)
Q: sore loser. とはどういう意味ですか?
A: Someone who reacts with jealousy or arrogance when they lose a game or a competition. Instead of being a 'good sport' (reacting to losing with humility and acceptance).


Q: looser と loser はどう違いますか?
A: 'Looser' refers to the degree of tightness of something, generally meaning a lesser degree of being 'loose'.

'Loser' refers to someone who doesn't win or more accurately generally comes last.
Q: loser と lose はどう違いますか?
A: Loser = いつも負ける人か不人気な人
Lose = 負けるか迷う
Probably best translations

I lose to him all the time. "彼にいつも負けちゃった。"

If I have a map, I won't lose my way. "地図を持てば、迷うことができません。"

He's a loser. "彼は不人気な人だ"

The loser is the person or thing that doesn't win. "勝たない人か物は敗者といいます。"
Q: "loser" と "underdog" はどう違いますか?
A: Underdog = less likely to win. Loser = actually lost or will actually lose. Loser is derogatory, underdog is not.


Q: 友達とゲームをしていて、自分が負けたからI'm loserと言ったら怒られました。自分に対してでもloserは言わない方がいい表現ですか? は 英語 (アメリカ) で何と言いますか?
A: 本当に怒られたのかな?「えーそんなこと言わないでよ!」って言われただけなのでは?

the をつけて I'm the loser ならまだしも、I'm a loser だと「どうせ負け犬だから」みたいな意味合いでも解釈てきるから、相手が「一回負けただけで決めつけるな」みたいな気持ちで諌めていたのかましれません。
Q: loser は 英語 (アメリカ) で何と言いますか?
A: QAの全文をご確認ください
Q: loser
は 英語 (アメリカ) で何と言いますか?
A: Loser, “he lost the game and now he’s a loser”
Q: loser は 英語 (イギリス) で何と言いますか?
A: you say loser in the UK too


Q: He has never been a loser at tennis. この表現は自然ですか?
A: "He has never lost at tennis."
Q: neither we nor they were losers. この表現は自然ですか?
A: Don't add were, just take the word out of the sentence
Q: I was afraid of her. I thought she thought of me as a loser. この表現は自然ですか?
A: I think "I was intimidated by her because I thought she thought of me as a loser" sounds a little more natural. I think in your sentence, "afraid" is too harsh a word.
Q: Can you change the "they, who have always been a loser" to in a word? like "a constantly loser(?)" something like that. I have no idea, but I want to say it in a short word naturally.
A: "They, ○○○ losers, are in the wrong" <-- this is an awkward sentence

"These losers are always in the wrong" is more natural.

You can say someone is "a constant loser" or someone "constantly loses" but there's no one specific word for it.
Q: She is loser. I'm loser.

It's created our couple.

A: She's a loser. I'm a loser. That's why we're a couple.