Idiom
that'll be the day
Meaning
Said in reply to something that one believes will never happen.
Meaning adapted from Wiktionary, available under CC BY-SA 4.0.
Examples
“"You'll tidy your room?" "That'll be the day."”
“When my brother said he would stop playing video games, I laughed and said, "That'll be the day."”
“She promised to arrive on time for once, and her skeptical colleague muttered under her breath, "That'll be the day."”
Examples
simple
“"You'll tidy your room?" "That'll be the day."”
contextual
“When my brother said he would stop playing video games, I laughed and said, "That'll be the day."”
complex
“She promised to arrive on time for once, and her skeptical colleague muttered under her breath, "That'll be the day."”
Origin
The expression originally referred to a significant day in the future regarded as worth waiting for. It is recorded as an idiom of anticipation, though its modern usage is more commonly reserved for events viewed as improbable.
Key words
Related idioms
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