Meaning
'That's a lie!' or, as an exclamation, 'no way!' / 'you're kidding!'. 'A lie yuh a tell' directly accuses someone of lying. But 'a lie!' on its own, said in astonishment, often just expresses stunned disbelief at surprising (even true) news — much like 'no way!' or 'get out of here!'. Tone tells whether it's an accusation or amazement.
Examples
-
A lie yuh a tell, mi never seh dat!
That's a lie you're telling; I never said that!
-
Dem win di lotto? A lie!
They won the lottery? No way!
-
A lie! Mi cyaan believe it.
No way! I can't believe it.
Origin
From 'a' (it is) + 'lie'; 'that's a lie', or an exclamation of disbelief. See [[a-true]], [[liard]].
How it’s used
'That's a lie!'; or, in astonishment, 'no way!'. See [[a-true]], [[liard]].