Once in a Blue Moon Idiom: Meaning, Definition & Synonyms

Introduction

The idiom “once in a blue moon” means something that happens very rarely. In IELTS writing and speaking, using such idiomatic expressions can enhance your language and make your responses more engaging. For example, in IELTS writing task 1 general letters,you might say, “I visit my grandparents once in a blue moon due to my busy schedule.” In , you could use it like this: “I go hiking once in a blue moon, but I always enjoy it when I do.” Proper use of idioms like this can demonstrate your proficiency and add color to your language, therefore helping you achieve a high IELTS band score in these modules.

Definition & Meaning

The  simplest meaning of “once in a blue moon” is: “Very rarely.”

The phrase implies that something happens so seldom that it’s as rare as a blue moon, which is an uncommon lunar phenomenon. When you say something happens “once in a blue moon,” you’re highlighting its rarity and infrequency.

History & Origins

The origins of this idiom date back to the 16th century. The term “blue moon” initially had nothing to do with the moon’s color but referred to an extra full moon that appeared in a season. Typically, each season has three full moons, but occasionally, a fourth would occur. This rare fourth moon was called a “blue moon.”

The phrase “once in a blue moon” began to be used metaphorically in the 19th century to describe any rare event. Over time, it evolved into the idiom we use today to indicate extreme rarity.

Modern Usage

Today, “once in a blue moon” is commonly used in everyday speech of IELTS Speaking part 1, IELTS Speaking part 2, and IELTS writing informal letters. Some examples of how it’s typically employed:

• I only eat fast food once in a blue moon, as I prefer cooking at home.
• She visits her hometown once in a blue moon since moving to the city.
• The antique shop gets truly valuable items once in a blue moon.
• Our football team wins a match once in a blue moon, unfortunately.
• He checks his old email account once in a blue moon, just in case.

The phrase is useful when you want to emphasize the rarity of an event or action, often with a slight exaggeration for effect.

Check out 9 IELTS Speaking IDIOMS for BAND 9 SCORE

Do You Know? 

Did you know that a “blue moon” doesn’t actually appear blue? The term refers to the second full moon in a calendar month, which occurs roughly every 2.5 years. The phrase “once in a blue moon” actually predates this definition and originally referred to absurd or impossible events, much like saying “when pigs fly.”

Practice Exercise

Here are some multiple-choice questions related to the idiom “once in a blue moon”

1. Which of the following is the closest meaning of the idiom “once in a blue moon”?

A. Happens every day

B. Happens once in a while

C. Happens very rarely

D. Happens never

2. Which of the following sentences uses the idiom “once in a blue moon” correctly?

A. I see my grandmother once in a blue moon.

B. I only get to eat pizza once in a blue moon.

C. I get to travel once in a blue moon.

D. I only get to go to the movies once in a blue moon.

3. Fill in the blank with the correct idiom: I only get to see my best friend ________.

A. once in a while

B. once in a blue moon

C. every day

D. once in a month

4. Which of the following is an example of something that happens once in a blue moon?

A. A solar eclipse

B. A full moon

C. A lunar eclipse

D. A meteor shower

5. Which of the following sentences is the most similar in meaning to “I only get to see my aunt once in a blue moon”?

A. I see my aunt every other week.

B. I see my aunt every few months.

C. I see my aunt every year or so.

D. I see my aunt once in a lifetime.

Answer Key 

1. The answer is (C). The idiom “once in a blue moon” means something that happens very rarely or infrequently. A blue moon is a full moon that occurs once in every 2.7 years, which is much less often than a regular full moon. So, option (C) is the closest meaning of the idiom.
2. The answer is (A). The sentence “I see my grandmother once in a blue moon” uses the idiom correctly to mean that the speaker only gets to see their grandmother very rarely. The other sentences do not use the idiom correctly.
3. The answer is (B). The idiom “once in a blue moon” is the best choice to fill in the blank because it means that the speaker only gets to see their best friend very rarely. The other options do not make sense in the context of the sentence.
4. The answer is (A). A solar eclipse is a rare event that occurs when the moon passes between the Earth and the sun. It only happens once every 18 months or so. The other options are not as rare as a solar eclipse.
5. The answer is (C). The sentence “I see my aunt every year or so” is the most similar in meaning to “I only get to see my aunt once in a blue moon” because it means that the speaker only gets to see their aunt very rarely. The other options do not make sense in the context of the sentence.

Conclusion

The significance of idioms in the IELTS exam cannot be overstated. Incorporating idioms into your IELTS Speaking and IELTS Writing tasks can elevate your score and make your communication more engaging and precise. However, it’s essential to use them judiciously and ensure they fit naturally within the context.

So, as you prepare for the IELTS exam, don’t underestimate the power of idioms in showcasing your language skills and making a lasting impression on the examiners.

Also, check

• ‘As Cool As A Cucumber’ Idiom: Meaning, Origin, Evolution & Exercise!
• A Dime A Dozen Idiom: Meaning, Origin, Evolution & Exercise!
• ‘Bob’s Your Uncle’ Idiom: Meaning, Origin, Evolution & Exercise
• The Sky is the Limit Idiom – Meaning, Definition & Synonyms
• Chew the Fat Idiom – Meaning, Definition & Synonyms