Idioms are the colorful shortcuts of English. They make your speech lively, help you sound natural, and connect you with culture. In this post, you'll learn six common idioms, where they come from, and how to use them correctly—plus practice right away with quick exercises.

What is an idiom?

An idiom is a fixed expression whose meaning is different from its literal words. For example, “break the ice” is not about real ice—it means start a friendly conversation to make people feel comfortable.

Why origins matter

Knowing where an idiom comes from makes it easier to remember and use. Many idioms come from ships, old voting systems, or the sky! When you know the story, the phrase sticks.

Idiom 1: Under the weather

Meaning: feel a bit sick or unwell.

Origin: Maritime English. Sailors who felt ill during rough conditions were sent below deck (under the weather), away from the wind and waves.

Use it to talk about mild illness, not serious medical situations.

I feel under weather. → I’m feeling under the weather. This idiom needs the article “the.”

Sorry, I can’t go out. I’m feeling today.

Idiom 2: Break the ice

Meaning: start a conversation or activity to reduce tension.

Origin: Ships breaking ice to open paths for travel. Later, people used it to describe opening social paths—making it easier to talk.

We played a quick game to before the meeting.

Idiom 3: A piece of cake

Meaning: very easy.

Origin: Linked to “cakewalk” contests in the 19th–20th century, where winners received cake. By the 1930s, Americans were using “a piece of cake” to mean something that is easy.

Idiom 4: Spill the beans

Meaning: reveal a secret.

Possible origin: In some ancient voting systems, people used beans to vote. If someone spilled the beans, the vote was revealed. The exact origin is debated, but the idea of “beans” and secrets is memorable.

Idiom 5: Once in a blue moon

Meaning: very rarely.

Origin: A “blue moon” refers to the second full moon in a calendar month, which happens rarely. So if something happens “once in a blue moon,” it is not common at all.

Idiom 6: Cost an arm and a leg

Meaning: very expensive.

Origin: The exact origin is unclear. It became common in the mid-20th century and strongly emphasizes a high price. (The story about portraits charging more for limbs is a popular myth, but not supported.)

It costs an arm and leg. → It costs an arm and a leg. Keep both articles: “an” and “a.”

Tone and register

Many idioms are informal or neutral. They are perfect for conversation, emails to friends, or social media. In very formal writing (academic reports), idioms may sound too casual.

Quick recap

• under the weather = feel a bit sick (maritime origin)
• break the ice = start friendly conversation (ships breaking ice)
• a piece of cake = very easy (linked to cakewalk contests)
• spill the beans = reveal a secret (possibly bean voting; debated)
• once in a blue moon = very rarely (astronomical event)
• cost an arm and a leg = very expensive (origin unclear)

Practice more

Try writing 3 sentences about your week using any two idioms. Keep the articles and word order fixed!

Final mini-test

Choose the best idiom for each sentence. Say your answers out loud!

1. The meeting was tense, so I told a funny story to ______.
2. That puzzle looked hard, but it was ______.
3. She asked me not to ______ about the promotion.
4. Tickets for the concert ______; I can’t afford them.

Check: 1) break the ice 2) a piece of cake 3) spill the beans 4) cost an arm and a leg

You’ve got this. With the stories behind these idioms, they’ll stick in your memory—and your everyday English.