came off

Roald Dahlの短編小説 "Claud's Dog" からの引用です。
Personally, I had my own career as a filling-station owner to keep me busy, not to mention second-hand cars, but if Claud wanted to fool around with dogs that was all right with me, especially a thing like today -- if it came off. As a matter of fact, I don't mind admitting that every time I thought about the money we were putting on and the money we might win, my stomach gave a little lurch.
"came off" は基本動詞の "come" が使われていますが、私の知らない表現です。辞書を見ます。
・Oxford English Dictionary: (of an action) succeed; be accomplished.: this was a bold experiment which did not come off

・Collins Dictionary: If something comes off, it is successful or effective.: It was a good try but it didn't quite come off.

・Cambridge English Dictionary: to happen as planned, or to succeed: I tried telling a few jokes but they didn't come off.
英語は難しいですね。

left out in the cold

Roald Dahlの短編小説 "Claud's Dog" からの引用です。
Claud stopped to catch his breath. He was having a vision now -- the same vision that accompanied all his dreams of wealth -- of an immense factory building with tall chimneys and hundreds of happy workers streaming through the wide wrought iron gates and Claud himself sitting in his luxurious office directing operations with a calm and splendid assurance.
"There's people with brains studying these things this very minute," he went on. "So you got to jump in quick unless you want to get left out in the cold. That's the quick before all the others, Mr. Hoddy."
"left out in the cold" は文字通りだと「寒い所に置き去りされる」となりますが、比喩表現としての慣用句の様です。辞書で確認します。
・Oxford English Dictionary: Ignored; neglected.: the talks left the French out in the cold

・Collins Dictionary: If you say that a person, group, or country has been left out in the cold, you mean that they have been ignored by others rather than being invited to take part in some activity with them.: Developing countries might be left out in the cold in current world trade talks.

mantle

Roald Dahlの短編小説 "Claud's Dog" からの引用です。
"You never know, you see. You could be sickenin for it weeks and weeks and not feel it. Then all of a sudden-bang!-and it's got you. That's why Doctor Arbuthnot's so articular. That's why he sent me out so quick, see. To stop the spreadin of disease.
He had now taken upon himself the mantle of the Health Officer. A most important rat he was now, deeply disappointed that we were not suffering from bubonic plague.
外套とか炉棚の "mantle" は知っていますが、上記の "mantle" は何か別の意味ですね。辞書を見ます。

・Oxford English Dictionary: An important role or responsibility that passes from one person to another.: The second son has now assumed his father's mantle.

・Collins Dictionary: If you take on the mantle of something such as a profession or an important job, you take on the responsibilities and duties which must be fulfilled by anyone who has this profession or job.: Glasgow has broadened its appeal since taking on the mantle of European City of Culture in 1990.

・Cambridge English Dictionary: the responsibilities of an important position or job, especially as given from the person who had the job to the person who replaces them: He has been asked to take on the mantle of managing director in the New York office.

putting salt on its tail

Roald Dahlの短編小説 "Nunc Dimittis" からの引用です。
“Is it not possible,” I said, “that a man might be — how shall I put it? — extremely fond of a lady and at the same time have his own good reasons for not wishing her to know about it yet?”
“More than possible, Mr Lampson.” with a man has to stalk his quarry with great caution, waiting patiently for the right moment to reveal himself.”
“Precisely, Mr Lampson.”
“There are better ways of catching a bird than by chasing it through the woods.”
“Yes, indeed, Mr Lampson.”
“Putting salt on its tail, for instance.”
“Ha-ha?”
“All right, Mr Royden, I think you understand. Now—do you happen by any chance to know a lady called Janet de Pelagia?”
「鳥を捕らえる」と言うのは女性の心を捕らえることの比喩表現ですが、その鳥を捕らえる良い方法に "Putting salt on its tail" があると言っています。これは慣用句か何かでしょうか？

・Farlex Dictionary of Idioms: obsolete To try to capture or encapsulate someone or something. An allusion to the folk method of capturing birds by sprinkling salt on their tail feathers.: We spend so much time putting salt on the tail of an ideal version of life—more money, more property, better status—that we forget to enjoy our present circumstances.
"Putting salt on its tail" の説明を掲載しているのは上記の辞書だけでしたが、Web上には次の様な話が一杯ありました。

When I was little 5-6 my dad told me if I wanted to catch a bird all I need to do was put salt on its tail end and I would be able to catch it because then it could not fly.I kept trying this for a couple of years.lol

protection racket

The Japan Times１月８日の記事を引用します。
Trump tries his protection racket on South Korea
Trump is demanding a five-fold increase in the roughly $1 billion that Seoul now pays annually in host-nation support for U.S. forces based in South Korea.
記事タイトルに使われている "protection racket" は記事内容からすると暴力団のみかじめ料を連想させます。
"protection racket" は7/12/2016にも取り上げていますが、アメリカファーストを連発するトランプ大統領の言動からして、同盟国でも "protection racket" を要求されていると感じても不思議ではないですね。

white horse

Roald Dahlの短編 "Dip in the Pool" からの引用です。
'The sun deck, please,' he said to the elevator man.
The wind caught him full in the face as he stepped out on to the open deck. He staggered and grabbed hold of the rail and held on tight with both hands, and he stood there looking out over the darkening sea where the great waves were welling up high and white horses were riding against the wind with plumes of spray behind them as they went.
上の文中に出て来た "white horses" ですが、文脈から白波を連想させます。辞書で確認します。
・Vocabulary.com: a wave that is blown by the wind so its crest is broken and appears white

・Collins Dictionary: a wave with a white broken crest

・Wiktionary: A wave that is blown by the wind such that its crest is broken up and appears white and foamy; a whitecap.

play with rabbits

Roald Dahlの短編 "My Lady Love, My Dove" からの引用です。
"Listen," she said, slapping down the magazine on her lap," you saw the sort of people they were as well as I did.
A pair of stupid climbers who think they can go anywhere just because they play good bridge."
"I'm sure you're right dear, but what I don't honestly understand is why — "
I keep telling you — so that for once we can get a decent game. I'm sick and tired of playing with rabbits. But I really can't see why I should have these awful people in the house."
カードゲームのブリッジをする話の延長なので、"playing with rabbits" は兎と遊ぶことではないのは確かです。下手な相手とブリッジするのに辟易しているので、ブリッジが上手いので呼んだが、気に入らない人達だとすると、つじつまが合います。ここでの "playing with rabbits" ブリッジの下手な人とゲームをする意味か、辞書で確認します。

・Collins Dictionary: a novice or poor performer at a game or sport

・Dictionary.com: a person who is poor at sports, esp. golf, tennis, or cricket.
"rabbit" は元々イギリス英語でイギリス発祥のスポーツが下手な人を指す意味があるのですね。

hammer them right home

Roald Dahlの短編集 "Someone Like You" を読み始めました。
その中の "Man from the South" からの引用です。
We stood there, the boy, the girl, and I, holding Martinis in our hands, watching the little man at work. We watched him hammer two nails into the table, about six inches apart. He didn't hammer them right home; he allowed a small part of each one to stick up.
一方は車を賭け、もう一方は金目の物を何も持たないで小指の切断を賭けるという、とんでもない話です。　引用文の "hammer them right home" の個所ですが、"them" は "two nails" を指しているので "hammer two nails right home" の意味が問題ですが、その後に "stick up" とあり、釘を完全に奥まで打たなかったことを意味していると推測できます。辞書で確かめます。 "home" の項に次の説明がありました。
・Collins Dictionary: to the fullest extent: hammer the nail home
・WordNet Search - 3.1: to the fullest extent; to the heart: "drove the nail home"; "drove his point home"; "his comments hit home"

・Wiktionary: to the place where it belongs; to the end of a course; to the full length: to drive a nail home; to ram a cartridge home; Eventually she managed to slide the lid of the pencil-box right home and the newt was hers.

Wiktionaryの最後の例文はRoald Dahlの作品、Matildaからの引用とありました。
10/19/2010に "nail goes home" を取り上げ、"hammer the nail home" も辞書で見ていましたね。

contronym

Reader's Digest １１月号の記事 'Words That Are Their Own Opposites' からの引用です。
A contronym is a word that is its own antonym. Sound unusual? You probablly use contronym every day ...
この後に "contronym" を使った例文が続きます。そうだなと思う例文の他に片方の意味を知らなかった例が二つありました。
- Dust can mean "to add dust" (to crops) or "to remove dust" (from furniture).
- Cleave can mean either "to cling/adhere" or "to split/sever."
私が知らなかったのは "dust" の次の用法と、
・Oxford English Dictionary: Cover lightly with a powdered substance.: Roll out on a surface dusted with flour.; Sprinkle (a powdered substance) on to something.: Orange powder was dusted over the upper body.
そして、"cleave" の次の意味でした。
・Oxford English Dictionary: Adhere strongly to (a particular pursuit or belief): Part of why we cleave to sports is that excellence is so measurable.; Become very strongly involved with or emotionally attached to (someone): It was his choice to cleave to the Brownings.
"contronym" は厄介な単語ですね。

zap/zapping

Reader's Digest １１月号の記事 'Live Long & Prosper' からの引用です。
GET ENOUGH REST
There's a growing amount of data linking sleep deprivation with disease and other health problems, says Scott Trappe, PhD, director of the human performance lab at Ball State University. Studies show that a lack of quality sleep zaps your energy, ups your stress level, hurts your memory, weakens your immune system, and makes you more anxious and depressed.
この "zap" の意味は文脈からだいたい分かりますが、一応辞書を見ます。
・Oxford English Dictionary: Destroy or obliterate.: Zap the enemy's artillery before it can damage your core units.

・Collins Dictionary: To zap someone or something means to kill, destroy, or hit them, for example with a gun or in a computer game.: A guard zapped him with the stun gun.

ところで、NHKニュース番組おはよう日本に「世界のメディアザッピング」のコーナーがあるのですが、最初このザッピングが聴き取れず、なんで日本語を使わないのか不思議に思っていました。
メディアザッピングに対応する意味の説明が "zap" にあるのか辞書を見ましたが、この意味での説明をしている辞書は見当たりません。（多くの辞書はTVのコマーシャル時にチャンネルを変える場合に "zap" を使う例を載せていますが）
しつこく調べると百科事典のWikipediaに次の説明がありました。
Channel surfing (also known as channel hopping or zapping) is the practice of quickly scanning through different television channels or radio frequencies to find something interesting to watch or listen to. Modern viewers, who may have cable or satellite services beaming down dozens if not hundreds or thousands of channels, are frequently channel surfing. It is common for people to scan channels when commercial broadcasters switch from a show over to running commercials.
NHKの「世界のメディアザッピング」は自社ではなく海外のTV局のニュースを幾つかさっと紹介しているのでこのザッピングを使っているのですね。それにしてもNHKならやはり適当な日本語を使えば良いと思うのですが。