# Phrase for saying something is impossible at all? [duplicate]

I am looking for good way of translating my native language way of saying something is impossible and will never be possible, i.e., Kan lungtat a par hunah le which literally means 'When our grindstone comes into blossom'. The grindstone which is used for sharpening knife can never sprout and grow tall and come into bloom. For example, So when someone asks for the impossible, we respond 'When our grindstone blooms' for emphasizing the impossibility. Is there an equivalent phrase in English?

• I don't think it is a possible duplicate because there may a time when the reed blooms and the cow comes home. But in my question, the grindstone can never bloom. – Mawia HL Nov 7 '16 at 19:34
• There are thousands of such in English. When pigs fly, when Hell freezes over, etc. People like to make them up. By the way, you can't use at all with impossible; incorporated negatives don't trigger the NPI. Not possible at all is fine, because the not trigger is unincorporated. – John Lawler Nov 7 '16 at 19:47

English idioms that emphasise the impossibility of an occurrence include:

• when Hell freezes over
• when pigs fly
• on the first of never
• it will be a cold day in Hell before [...]
• not in a million years
• never in a million years

When Hell freezes over and it will be a cold day in Hell refer to the image of Hell as a fiery place in Christian culture. Some religious people consider such light use of the word Hell disrespectful, but they are common idioms regardless. On the first of never uses never as if it were the name of a month.

If you prefer a less colourful way to emphasise never, you can use:

• never ever
• absolutely never
• definitely never
• Didn't you agree with the suggested duplicate's being a duplicate? These answers were mostly given there. – Edwin Ashworth Nov 8 '16 at 0:46
• The asker explained why they aren't duplicates. – J. Siebeneichler Nov 8 '16 at 1:13
• No, the OP explained why they considered them not to be. Equivalents for the 'when pigs fly' impossibility were given there. – Edwin Ashworth Nov 8 '16 at 1:24