informal10K+

UK//ðætəl bi ðə deɪ//US//ðætəl bi ðə deɪ//

Meaning of That'll be the day

An expression indicating that something is unlikely to happen.

In simple words: A phrase used to express doubt that something will happen.

That'll be the day in a sentence

  • He thinks he will win the lottery? That'll be the day.
  • You think she’ll agree to that? That'll be the day!
  • She claims he’ll actually change his mind. That'll be the day!
  • When pigs fly, that'll be the day we see him on time.

How to use That'll be the day

Used in conversational contexts, often when discussing something unlikely to happen. Avoid in formal writing.

Grammar pattern

standalone phrase

Memory hint

Imagine a day that will never come, like a dream.

Related words

Collocations with That'll be the day

  • say that'll be the day
  • believe that'll be the day
  • think that'll be the day

Synonyms for That'll be the day

Common mistakes with That'll be the day

  • Misusing it as a literal prediction instead of expressing skepticism.
  • Using it in serious or formal discussions where it may seem dismissive.

Compare That'll be the day with Impossible, Yeah right

That'll be the day appears in

That'll be the day in other languages

More chunks like That'll be the day

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Frequently asked questions about That'll be the day

What does That'll be the day mean?

A phrase used to express doubt that something will happen.

What is the definition of That'll be the day?

An expression indicating that something is unlikely to happen.

How do you use That'll be the day in a sentence?

He thinks he will win the lottery? That'll be the day.

Can you give another example of That'll be the day?

You think she’ll agree to that? That'll be the day!

What are synonyms for That'll be the day?

Common alternatives include not a chance, impossible, yeah right.

What words go with That'll be the day?

It commonly pairs with say that'll be the day, believe that'll be the day, think that'll be the day.

What are common mistakes when using That'll be the day?

Misusing it as a literal prediction instead of expressing skepticism. Using it in serious or formal discussions where it may seem dismissive.

How do you pronounce That'll be the day?

US: //ðætəl bi ðə deɪ//, UK: //ðætəl bi ðə deɪ//. Listen to the audio above to hear native pronunciation.

Is That'll be the day formal or informal?

"That'll be the day" is informal, so it fits casual conversation with friends and family.

When should I use That'll be the day?

Used in conversational contexts, often when discussing something unlikely to happen. Avoid in formal writing.